Rules for the Direction of the Mind
Descartes
Rule 1.
The end of study should be to direct the mind towards the enunciation of sound and correct judgement on all matters that come before it.
Whenever men notice some similarity between two things, they are wont to ascribe to each, even in those respects to which the two differ, what they have found to be true of the other. Thus they erroneously compare the sciences, which entirely exist in the cognitive exercise of the mind, with the arts, which depend upon an exercise and disposition of the body. They see that not all the arts can be acquired by the same man, but that he who restricts himself to one, most readily becomes the best executant, since it is not so easy for the same hand to adapt itself both to agricultural operations and to harp-playing, or to the performance of several such tasks as to one alone. Hence they have held the same to be true of the sciences also, and distinguishing them from one another according to their subject matter, they have imagined that they ought to be studied separately, each in isolation from all the rest. But this is certainly wrong. For since the sciences taken all together are identical with human wisdom, which always remains one and the same, however applied to different subjects, and suffers no more differentiation proceeding from them than the light of the sun experiences from the variety of the things which it illuminates, there is no need for minds to be confined at all within limits; for neither does the knowing of one truth have an effect like that of the acquisition of one art and prevent us from finding out another, it rather aids us to do so. Certainly it appears to me strange that so many people should investigate human customs with such care, the virtues of plants, the motions of the stars, the transmutations of metals, and the objects of similar sciences, while at the same time practically none bethink themselves about good understanding. Wisdom, though nevertheless all other studies are to be esteemed not so much for their own value as because they contribute something to this. Consequently we are justified in bringing forward this as the first rule of all, since there is nothing more prone to turn us aside from the correct way of seeking out truth than this directing of our inquiries, not towards their general end, but towards certain, special investigations. I do not here refer to perverse and censurable pursuits like empty glory or base gain; obviously counterfeit reasonings and quibbles suited to vulgar understanding open up a much more direct route to such a goal than does a sound apprehension of the truth. But I have in view even honourable and laudable pursuits, because these mislead us in a more subtle fashion. For example take our investigations of those sciences conducive to the conveniences of life or which yield that pleasure which is found in the contemplation of truth, practically the only joy in life that is complete and untroubled with any pain. There we may indeed expect to receive the legitimate fruits of scientific inquiry; but if, in the course of our study, we think of them, they frequently cause us to omit many facts which are necessary to the understanding of other matters, because they seem to be either of slight value or of little interest. Hence we must believe that all the sciences are so inter-connected, that it is much easier to study them all together than to isolate one from all the others. If, therefore, anyone wishes to search out the truth of things in serious earnest, he ought not to select one special science; for all the sciences are conjoined with each other and interdependent: he ought rather to think how to increase the natural light of reason, not for the purpose of resolving this or that difficulty of scholastic type, but that his understanding may light his will to its proper choice in all the contingencies of life. In a short time he will see with amazement that he has made much more progress than those who are eager about particular ends, and that he has not only obtained all that they desire, but even higher results than fall within his expectation.
Rule II.
Only those objects should engage our attention, to the sure and indubitable knowledge of which our mental powers seem to be adequate.
Science in its entirety is true and evident cognition. He is no more learned who has doubts on many matters than the man who has never thought of them; nay he appears to be less learned if he has formed wrong opinions on any particulars. Hence it were better not to study at all than to occupy one's self with objects of such difficulty, that, owing to our inability to distinguish true from false, we are forced to regard the doubtful as certain; for in those matters, any hope of augmenting our knowledge is exceeded by the risk of diminishing it. Thus in accordance with the above maxim we reject all such merely probable knowledge and make it a rule to trust only what is completely known and incapable of being doubted. No doubt men of education may persuade themselves that there is but little of such certain knowledge, because, forsooth, a common failing of human nature has made them deem it too easy and open to everyone, and so led them to neglect to think upon such truths; but I nevertheless announce that there are more of these than they think --truths which suffice to give a rigorous demonstration of innumerable propositions, the discussion of which they have hitherto been unable to free from the element of probability. Further, because they have believed that it was unbecoming for a man of education to confess ignorance on any point, they have so accustomed themselves to trick out their fabricated explanations, that they have ennded by gradually imposing on themselves and thus have issued them to the public as genuine.
But if we adhere closely to this rule we shall find left but few objects of legitimate study. For there is scarce any question occurring in the sciences about which talented men have not disagreed. But whenever two men come to opposite decisions about the same matter one of them at least must certainly be in the wrong, and apparently there is not even one of them who knows; for if the reasoning of the second were sound and clear he would be able so to lay it before the other to succeed in convincing his understanding also. Hence apparently we cannot attain to a perfect knowledge in any such case of probable opinion, for it would be rashness to hope for more than others have attained to. Consequently if we reckon correctly, of the sciences already discovered, Arithmetic and Geometry alone are left, to which the observance of this rule reduces us.
Yet we do not therefore condemn that method of philosophizing which others have already discovered, and those weapons of the schoolmen, probable syllogisms, which are so well suited for polemics. They indeed give practice to the wits of youth and, producing emulation among them, act as a stimulus; and it is much better for their minds to be moulded by opinions of this sort, uncertain though they appear, as being objects of controversy amongst the learned, than to be left entirely to their own devices. For thus through lack of guidance they might stray into some abyss, but as long as they follow in their masters' footsteps, though they may diverge at times from the truth, they will yet certainly find a path which is at least in this respect safer, that it has been approved by more prudent people. We ourselves rejoice that we in earlier years experienced this scholastic training; but now, being released from that oath of allegiance which bound us to our old masters and since, as become our riper years, we are no longer subject to the ferule, if we wish in earnest to establish for ourselves those rules which shall aid us in scaling the heights of human knowledge, we must admit assuredly among the primary members of our catalogue that maxim which forbids us to abuse our leisure as many do, who neglect all easy quests and take up their time only with difficult matters; for they, though certainly making all sorts of subtle conjectures and elaborating most plausible arguments with great ingenuity, frequently find too late that after all their labours they have only increased the multitude of their doubts, without acquiring any knowledge whatsoever.
But now let us proceed to explain more carefully our reason for saying , as we did a little while ago, that of all the sciences known as yet, Arithmetic and Geometry alone are free from any taint of falsity or uncertainty. We must note then that there are two ways by which we arrive at the knowledge of facts, viz. by experience and by deduction. We must further observe that while our inferences from experience are frequently fallacious, deduction, or the pure illation of one thing from another, though it may be passed over, if it is not seen through, cannot be erroneous when performed by an understanding that is in the least degree rational. And it seems to me that the operation is profited but little by those constraining bonds by means of which the Dialecticians claim to control human reason, though I do not deny that that discipline may be serviceable for other purposes. My reason for saying so is that none of the mistakes which men can make (men, I say, not beasts) are due to faulty inference; they are caused merely by the fact that we found upon a basis of poorly comprehended experiences, or that propositions are posited which are hasty and groundless.
This furnishes us with an evident explanation of the great superiority in certitude of arithmetic and Geometry to other sciences. The former alone deal with an object so pure and uncomplicated, that they need make no assumptions at all which experience renders uncertain, but wholly consist in the rational deduction of consequences. They are on that account much the easiest and clearest of all, and possess an object such as we require, for in them it is scarce humanly possible for anyone to err except by inadvertence. And yet we should not be surprised to find that plenty of people of their own accord prefer to apply their intelligence to other studies, or to Philosophy. The reason for this is that every person permits himself the liberty of making guesses in the matter of an obscure subject with more confidence than in one which is clear, and that it is much easier to have some vague notion about any subject, no matter what, than to arrive at the real truth about a single question however simple that may be.
But one conclusion now emerges out of these considerations, viz. not, indeed, that Arithmetic and Geometry are the sole sciences to be studied, but only that in our search for the direct road towards truth we should busy ourselves with no object about which we cannot attain a certitude equal to that of the demonstrations of Arithmetic and Geometry.
Rule III.
In the subjects we propose to investigate, our inquiries should be directed, not to what others have thought, not to what we ourselves conjecture, but to what we can clearly and perspicuously behold and with certainty deduce; for knowledge is not won in any other way.
To STUDY the writings of ancients is right, because it is a great boon for us to be able to make use of the labours of so many men; and we should do so, both in order to discover what they have correctly made out in previous ages, and also that we may inform ourselves as to what in the various sciences is still left for investigation. But yet there is a great danger lest in a too absorbed study of these works we should become infected with their errors, guard against them as we may. For it is the way of writers, whenever they have allowed themselves rashly and credulously to take up a position in any controverted matter, to try with the subtlest arguments to compel us to go along with them. But when, on the contrary, they have happily come upon something certain and evident, in displaying it they never fail to surround it with ambiguities, fearing, it would seam, lest the simplicity of their explanation should make us respect their discovery less, or because they grudge us an open vision of the truth.
Further, supposing now that all were wholly open and candid, and never thrust upon us doubtful opinions as true, but expounded every matter in good faith, yet since scarce anything has been asserted by any one man the contrary of which has not been alleged by another, we should be eternally uncertain which of the two to believe. It would be no use to total up the testimonies in favour of each, meaning to follow that opinion which was supported by the greater number of authors: for if it is a question of difficulty that is in dispute, it is more likely that the truth would have been discovered by few than by many. But even though all these men agreed among themselves, what they teach us would not suffice for us. For we shall not e.g. all turn out to be mathematicians though we know by heart all the proofs that other have elaborated, unless we have an intellectual talent that fits us toresolve difficulties of any kind. Neither, though we have mastered all the arguments of Plato and Aristotle, if yet we have not the capacity for passing a solid judgment on these matters, shall we become Philosophers; we should have acquired the knowledge not of science, but of history.
I lay down the rule also, that we must wholly refrain from ever mixing up conjectures with our pronouncements on the truth of things. This warning is of no little importance. There is no stronger reason for our finding nothing in the current Philosophy which is so evident and certain as not to be capable of being controverted, than the fact that the learned, not content with the recognition of what is clear and certain, in the first instance hazard the assertion of obscure and ill-comprehended theories, at which they have arrived merely by probable conjecture. Then afterwards they gradually attach complete credence to them, and mingling them promiscuously with what is true and evident, they finish by being unable to deduce any conclusion which does not appear to depend upon some proposition of the doubtful source and hence is not uncertain.
But lest we in turn should slip into the same error, we shall here take note of all those mental operations by which we are able, wholly without fear or illusion, to arrive at the knowledge of things. Now I admit only two, viz. intuition and induction. (Sense here seems to require "deduction.")
By intuition I understand, not the fluctuating testimony of the senses, not the misleading judgment that proceeds from the blundering constructions of imagination, but the conception which an unclouded and attentive mind gives us so readily and distinctly that we are wholly freed from doubt about that which we understand. Or, what comes to the same thing, intuition is the undoubting conception of an unclouded and attentive mind, and springs from the light of reason alone; it is more certain than deduction itself, in that it is simpler, though deduction, as we have noted above, cannot by us be erroneously conducted. Thus each individual can mentally have intuition of the fact that he exists, and that he thinks; that the triangle is bounded by three lines only, the sphere by a single superficies, and so on. Facts of such kind are far more numerous than many people think, disdaining as they do to direct their attention upon such simple matters.
But in case anyone may be put out by this new use of the term intuition and of other terms which in the following pages I am similarily compelled to dissever from their current meaning. I here make the general announcement that I pay no attention to the way in which particular terms have of late been employed in the schools, because it would have been difficult to employ the same terminology while my theory was wholly different. All I take note of is the meaning of the Latin of each word, when, in cases where an appropriate term is lacking, I wish to transfer to the vocabulary that expresses my own meaning thoses that I deem most suitable.
This evidence and certitude, however, which belongs to intuition, is required not only in the enunciation of propositions, but also in discursive reasoning of whatever sort. For example consider the consequence: 2 and 2 amount to the same 3 and 1. Now we need to see intuitively not only that 2 and 2 make 4, and that likewise 3 and 1 make 4, but further that the third of the above statements is a necessary conclusion from these two.
Hence now we are in a position to raise the wuestion as to why we have, besides intuition, given this supplementary method of knowing, viz. knowing by deduction by which we understand all necessary inferencefrom other facts which are known with certainty. This, however, we could not avoid, because many things are known with certainty, though not by themselves evident, but only deduced from true and known principles by the continuous and uninterrupted action of a mind that has a clear vision of each step in the process. It is in a similar way that we know that the last link in a long chain is connected with the first, even though we do not take in by means of one and the same act of vision all the intermediate links on which that connection depends, but only remember that we have taken them successively under review and that each single on eis united to its neighbor, from the first even to the last. Hence we distinguish this mental intuition from deduction by the fact that into the conception of the latter there enters a certain movement or succession, into that of the former there does not. Further deduction does not require an immediately presented evidence such as intuition possesses; its certitude is rather conferred upon it in some way by memory. The upshot of the matter is that it is possible to say that those propositions indeed which are immediately deduced from first principles are known now by intuition, now by deduction, i.e. in a way that differs according to our point of view. But the first principles themselves are given by intuition alone, while, on the contrary, the remote conclusions are furnished only by deduction.
These two methods are the most certain routes to knowledge, and the mind should admit no others. All the rest should be rejected as suspect of error and dangerous. But this does not prevent us from believing matters that have been divinely revealed as being more certain than our surest knowledge, since belief in these things, as all faith in obscure matters, is an action, not of our intelligence, but of our will. They should be heeded also since, if they have any basis in our understanding, they can and ought to be, more than all things else, discovered by one of the ways abovementioned, as we hope perhaps to show at greater length on some future opportunity.
Rule IV.
There is need of a method for finding out the truth.
So blind is the curiosity by which mortals are possessed, that they often conduct their minds along unexplored routes, having no reason to hope for success, but merely being willing to risk the experiment of finding whether the truth they seek lies there. As well might a man burning with no unintelligent desire to find treasure, continuously roam the streets, seeking to find something that a passer by might have chanced to drop. This is the way in which most Chemists, many Geometricians, and Philosophers not a few prosecute their studies. I do not deny that sometimes in these wanderings they are lucky enough to find something true. But I do not allow that this argues greater industry on their part, but only better luck. But however that may be, it were far better never to think of investigating truth at all, than to do so without a method. For it is very certain that unregulated inquiries and confused reflections of this kind only confound the natural light and blind our mental powers. Those who so become accustomed to walk in darkness weaken their eye-sight so much that afterwards they cannot bear the light of day. This is confirmed by experience; for how often do we not see that those who have never taken to letters, give a sounder and clearer decision about obvious matters than those who have spent all their time in the schools? Moreover by a method I mean certain and simple rules, such that, if a man observe them accurately, he shall never assume what is false is true, and will never spend his mental efforts to no purpose, but will always gradually increase his knowledge and so arrive at a true understanding of all that does not surpass his powers.
These two points must be carefully noted, viz. never to assume what is false as true, and to arrive at a knowledge which takes in all things. For, if we are without the knowledge of any of the things which we are capable of understanding, that is only because we have never perceived any way to bring us to this knowledge, or because we have fallen into the contrary error. But if our method rightly explains how our mental vision should be used, so as not to fall into the contrary error, and how deduction should be discovered in order that we may arrive at the knowledge of all things, I do not see what else is needed to make it complete; for I have already said that no science is acquired except by mental intuition or deduction. There is besides no question of extending it further in order to show how these said operations ought to be effected, because they are the most simple and primary of all. Consequently, unless our understanding were already able to employ them, it could comprehend none of the precepts of that very method, not even the simplest. Bus as for the other mental operations, which Dialectic does its best to direct by making use of these prior ones, they are quite useless here, rather they are to be accounted impediments, because nothing can be added to the pure light of reason which does not in some way obscure it.
Since then the usefulness of this method is so great that without it study appears to be harmful than profitable, I am quite ready to believe that the greater minds of former ages had some knowledge of it, nature even conducting them to it. For the human mind has in it something that we may call devine, wherein are scattered the first germs of useful modes of thought. Consequently it often happens that however much neglected and choked by interfering studies they bear fruit of their own accord. Arithmetic and Geometry, the simplest sciences, give us an instance of this; for we have sufficient evidence that the ancient Geometricians made use of a certain analysis which they extended to the resolution of all problems, though they grudged the secret to posterity. At the present day also there flourishes a certain kind of arithmetic, called Algebra, which designs to effect, when dealing with numbers, what the ancients achieved in th ematter of figures. These two methods are nothing else than the spontaneous fruit sprung from the inborn principles of the discipline here in question; and I do not wonder that these sciences with their very simple subject matter should have yielded results so much more satisfactory than others in which greater obstructions choke all growth. But even in the latter case, if only we take care to cultivate them assiduously, fruits will certainly be able to come to full maturity.
This is the chief result which I have had in view in writing this treatise. For I should not think much of these rules, if they had no utility save for the solution of the empty problems with which Logicians and Geometers have been wont to beguile their leisure; my only achievement thus would have seemed to be an ability to argue about trifles more subtly than others. Further, though much mention is here made of numbers and figures, because no other sciences furnish us with illustrations of such self-evidence and certainty, the reader who follows my drift with sufficient attention will easily see that nothing is less in my mind than ordinary Mathematics, and that I am expounding quite another science, of which these illustrations are rather the outer husk than the constituents. Such a science should contain the primary rudiments of human reason, and its province ought to extend to the eliciting of true results in every subject. To speak freely, I am convinced that it is a more powerful instrument of knowledge than any other that has been bequeathed to us by human agency, as being the source of all others. But as for the outer covering I mentioned, I mean not to employ it to cover up and conceal my method for the purpose of warding of the vulgar; rather I hope so to clothe and embellish it that I may make it more suitable for presentation to the human mind.When first I applied my mind to Mathematics I read straight away most of what is usually given by the mathematical writers, and I paid special attention to Arithmetic and Geometry, because they were said to be the simplest and so to speak the way to all the rest. But in neither case did I then meet with authors who fully satisfied me. I did indeed learn in their works many propositions about numbers which I found on calculation to be true. As to figures, they in a sense exhibited to my eyes a great number of truths and drew conclusions from certain consequences. But they did not seem to make it sufficiently plain to the mind itself why those things are so, and how they discovered them. Consequently I was not
surprised that many people, even of talent and scholarship, should, after glancing at these sciences, have either given them up as being empty and childish or, taking them to be very difficult and intricate, been deterred at the very outset from learning them. For really there is nothing more futile than to busy one's self with bare numbers and imaginary figures in such a way as to appear to rest content with such trifles, and so to resort to those superficial
demonstrations, which are discovered more frequently by chance than by skill, and are a matter more of the eyes and the imagination than of the understanding, that in a sense one ceases to make use of one's reason. I might
add that there is no more intricate task than
that of solving by this method of proof new
difficulties that arise, involved as they are with
numerical confusions. But when I afterwards
bethought myself how it could be that the
earliest pioneers of Philosophy in bygone ages
refused to admit to the study of wisdom any
one who was not versed in Mathematics, evidently
believing that this was the easiest and
most indispensable mental exercise and preparation
for laying hold of other more important
sciences, I was confirmed in my suspicion that
they had knowledge of a species of Mathematics
very different from that which passes
current in our time. I do not indeed imagine
that they had a perfect knowledge of it, for
they plainly show how little advanced they
were by the insensate rejoicings they display
and the pompous thanksgivings they offer for
the most trifling discoveries. I am not shaken
in my opinion by the fact that historians make
a great deal of certain machines of theirs. Possibly
these machines were quite simple, and
yet the ignorant and wonder-loving multitude
might easily have lauded them as miraculous.
But I am convinced that certain primary
germs of truth implanted by nature in human
minds—though in our case the daily reading
and hearing of innumerable diverse errors
stifle them—had a very great vitality in that
rude and unsophisticated age of the ancient
world. Thus the same mental illumination
which let them see that virtue was to be preferred
to pleasure, and honour to utility, although
they knew not why this was so, made
them recognize true notions in Philosophy and
Mathematics, although they were not yet able
thoroughly to grasp these sciences. Indeed I
seem to recognize certain traces of this true
Mathematics in Pappus and Diophantus, who
though not belonging to the earliest age, yet
lived many centuries before our own times.
But my opinion is that these writers then with
a sort of low cunning, deplorable indeed, suppressed
this knowledge. Possibly they acted
just as many inventors are known to have done
in the case of their discoveries, i.e. they feared
that their method being so easy and simple
would become cheapened on being divulged,
and they preferred to exhibit in its place certain
barren truths, deductively demonstrated
with show enough of ingenuity, as the results
of their art, in order to win from us our admiration
for these achievements, rather than to
disclose to us that method itself which would
have wholly annulled the admiration accorded.
Finally there have been certain men of talent
who in the present age have tried to revive
this same art. For it seems to be precisely that
science known by the barbarous name Algebra
if only we could extricate it from that vast array of
numbers and inexplicable figures by which it is overwhelmed, so that it might display the clearness and simplicity which, we imagine ought to exist in a genuine Mathematics.
It was these reflections that recalled me
from the particular studies of Arithmetic and
Geometry to a general investigation of Mathematics.
and thereupon I sought to determine
what precisely was universally meant by that
term, and why not only the above mentioned
sciences, but also Astronomy, Music, Optics,
Mechanics and several others are styled parts of Mathematics. Here indeed it is not enough to look at the origin of the word; for since the name "Mathematics" means exactly the same thing as "scientific study," these other branches could, with as much right as Geometry itself,
be called Mathematics. Yet we see that almost
anyone who has had the slightest schooling,
can easily distinguish what relates to Mathematics
in any question from that which belongs
to the other sciences. But as I considered the
matter carefully it gradually came to light that
all those matters only were referred to Mathematics in which order and measurement are investigated,
and that it makes no difference whether it be in numbers, figures, stars, sounds
or any other object that the question of measurement
arises. I saw consequently that there
must be some general science to explain that
element as a whole which gives rise to problems
about order and measurement, restricted
as these are to no special subject matter. This,
I perceived, was called "Universal Mathematics,"
not a far fetched designation, but one
of long standing which has passed into current
use, because in this science is contained everything
on account of which the others are called
parts of Mathematics. We can see how much it
excels in utility and simplicity the sciences
subordinate to it, by the fact that it can deal
with all the objects of which they have cognizance
and many more besides, and that any
difficulties it contains are found in them as
well, added to the fact that in them fresh difficulties
arise due to their special subject matter
which in it do not exist. But now how comes
it that though everyone knows the name of
this science and understands what is its province
even without studying it attentively, so
many people laboriously pursue the other dependent
sciences, and no one cares to master
this one? I should marvel indeed were I not
aware that everyone thinks it to be so very
easy, and had I not long since observed that
the human mind passes over what it thinks it
can easily accomplish, and hastens straight
away to new and more imposing occupations.
I, however, conscious as I am of my inadequacy,
have resolved that in my investigation
into truth I shall follow obstinately such an
order as will require me first to start with what
is simplest and easiest, and never permit me to
proceed farther until in the first sphere there
seems to be nothing further to be done. This is
why up to the present time to the best of my
ability I have made a study of this universal
Mathematics; consequently, I believe that
when I go on to deal in their turn with more
profound sciences, as I hope to do soon, my efforts
will not be premature. But before I make
this transition I shall try to bring together and
arrange in an orderly manner, the facts which
in my previous studies I have noted as being
more worthy of attention. Thus I hope both
that at a future date, when through advancing
years my memory is enfeebled, I shall, if need
be, conveniently be able to recall them by
looking in this little book, and that having now
disburdened my memory of them I may be
free to concentrate my mind on my future
studies.
RULE V
Method consists entirely in the order and disposition
of the objects towards which our mental
vision must be directed if we would find out any
truth. We shall comply with it exactly if we reduce
involved and obscure propositions step by
step to those that are simpler, and then starting
with the intuitive apprehension of all those that
are absolutely simple, attempt to ascend to the
knowledge of all others by precisely similar steps.
IN THIS alone lies the sum of all human endeavour,
and he who would approach the investigation
of truth must hold to this rule as
closely as he who enters the labyrinth must
follow the thread which guided Theseus. But
many people either do not reflect on the precept
at all, or ignore it altogether, or presume
not to need it. Consequently, they often investigate
the most difficult questions with so
little regard to order, that, to my mind, they
act like a man who should attempt to leap with
one bound from the base to the summit of a
house, either making no account of the ladders
provided for his ascent or not noticing them.
It is thus that all Astrologers behave, who,
though in ignorance of the nature of the heavens,
and even without having made proper
observations of the movements of the heavenly
bodies, expect to be able to indicate their effects.
This is also what many do who study
Mechanics apart from Physics, and rashly set
about devising new instruments for producing
motion. Along with them go also those Philosophers
who, neglecting experience, imagine
that truth will spring from their brain like
Pallas from the head of Zeus.
Now it is obvious that all such people violate
the present rule. But since the order here
required is often so obscure and intricate that
not everyone can make it out, they can scarcely
avoid error unless they diligently observe what
is laid down in the following proposition.
RULE VI
In order to separate out what is quite simple from
what is complex, and to arrange these matters
methodically, we ought, in the case of every series
in which we have deduced certain facts the one
from the other, to notice which fact is simple, and
to mark the interval, greater, less, or equal, which
separates all the others from this.
ALTHOUGH this proposition seems to teach
nothing very new, it contains, nevertheless,
the chief secret of method, and none in the
whole of this treatise is of greater utility. For
it tells us that all facts can be arranged in certain
series, not indeed in the sense of being referred
to some ontological genus such as the
categories employed by Philosophers in their
classification, but in so far as certain truths
can be known from others; and thus, whenever
a difficulty occurs we are able at once to
perceive whether it will be profitable to examine
certain others first, and which, and in
what order.
Further, in order to do that correctly, we
must note first that for the purpose of our procedure,
which does not regard things as isolated
realities, but compares them with one another
in order to discover the dependence in
knowledge of one upon the other, all things can
be said to be either absolute or relative.
I call that absolute which contains within itself
the pure and simple essence of which we are
in quest. Thus the term will be applicable to
whatever is considered as being independent,
or a cause, or simple, universal, one, equal,
like, straight, and so forth; and the absolute I
call the simplest and the easiest of all, so that
we can make use of it in the solution of questions.
But the relative is that which, while participating
in the same nature, or at least sharing
in it to some degree which enables us to relate
it to the absolute and to deduce it from that
by a chain of operations, involves in addition
something else in its concept which I call relativity.
Examples of this are found in whatever
is said to be dependent, or an effect, composite,
particular, many, unequal, unlike, oblique,
etc. These relatives are the further removed
from the absolute, in proportion as they contain
more elements of relativity subordinate
the one to the other. We state in this rule that
these should all be distinguished and their correlative
connection and natural order so observed,
that we may be able by traversing all
the intermediate steps to proceed from the
most remote to that which is in the highest degree
absolute.
Herein lies the secret of this whole method,
that in all things we should diligently mark
that which is most absolute. For some things
are from one point of view more absolute than
others, but from a different standpoint are
more relative. Thus though the universal is
more absolute than the particular because its
essence is simpler, yet it can be held to be
more relative than the latter, because it depends
upon individuals for its existence, and
so on. Certain things likewise are truly more
absolute than others, but yet are not the most
absolute of all. Thus relatively to individuals,
species is something absolute, but contrasted
with genus it is relative. So too, among things
that can be measured, extension is something
absolute, but among the various aspects of
extension it is length that is absolute, and so
on. Finally also, in order to bring out more
clearly that we are considering here not the
nature of each thing taken in isolation, but the
series involved in knowing them, we have purposely
enumerated cause and equality among
our absolutes, though the nature of these terms
is really relative. For though Philosophers
make cause and effect correlative, we find that
here even, if we ask what the effect is, we must
first know the cause and not conversely. Equals
too mutually imply one another, but we can
know unequals only by comparing them with
equals and not per contra.
Secondly, we must note that there are but
few pure and simple essences, which either our
experiences or some sort of light innate in us
enable us to behold as primary and existing
per se, not as depending on any others. These
we say should be carefully noticed, for they
are just those facts which we have called the
simplest in any single series. All the others can
only be perceived as deductions from these,
either immediate and proximate, or not to be
attained save by two or three or more acts of
inference. The number of these acts should be
noted in order that we may perceive whether
the facts are separated from the primary and
simplest proposition by a greater or smaller
number of steps. And so pronounced is everywhere
the inter-connection of ground and consequence, which gives rise, in the objects to be
examined, to those series to which every inquiry
must be reduced, that it can be investigated
by a sure method. But because it is not
easy to make a review of them all, and besides,
since they have not so much to be kept in the
memory as to be detected by a sort of mental
penetration, we must seek for something which
will so mould our intelligence as to let it perceive
these connected sequences immediately
whenever it needs to do so. For this purpose I
have found nothing so effectual as to accustom
ourselves to turn our attention with a sort of
penetrative insight on the very minutest of the
facts which we have already discovered.
Finally, we must in the third place note that
our inquiry ought not to start with the investigation
of difficult matters. Rather, before
setting out to attack any definite problem, it
behoves us first, without making any selection,
to assemble those truths that are obvious
as they present themselves to us, and afterwards,
proceeding step by step, to inquire
whether any others can be deduced from these,
and again any others from these conclusions
and so on, in order. This done, we should attentively
think over the truths we have discovered
and mark with diligence the reasons
why we have been able to detect some more
easily than others, and which these are. Thus,
when we come to attack some definite problem
we shall be able to judge what previous questions
it were best to settle first. For example, if
it comes into my thought that the number 6 is
twice 3,1 may then ask what is twice 6, viz. 12;
again, perhaps I seek for the double of this,
viz. 24, and again of this, viz. 48. Thus I may
easily deduce that there is the same proportion
between 3 and 6, as between 6 and 12, and
likewise 12 and 24, and so on, and hence that
the numbers 3, 6, 12, 24, 48, etc. are in continued
proportion. But though these facts are
all so clear as to seem almost childish, I am
now able by attentive reflection to understand
what is the form involved by all questions that
can be propounded about the proportions or
relations of things, and the order in which they
should be investigated; and this discovery embraces
the sum of the entire science of Pure
Mathematics.
For first I perceive that it was not more difficult
to discover the double of six than that of
three; and that equally in all cases, when we
have found a proportion between any two
magnitudes, we can find innumerable others
which have the same proportion between them.
So, too, there is no increase of difficulty, if three,
or four, or more of such magnitudes are sought
for, because each has to be found separately
and without any relation to the others. But
next I notice that though, when the magnitudes
3 and 6 are given, one can easily find a
third in continued proportion, viz. 12, it is yet
not equally easy, when the two extremes, 3
and 12, are given, to find the mean proportional,
viz. 6. When we look into the reason for
this, it is clear that here we have a type of difficulty
quite different from the former; for, in
order to find the mean proportional, we must
at the same time attend to the two extremes
and to the proportion which exists between
these two in order to discover a new ratio by
dividing the previous one; and this is a very
different thing from finding a third term in
continued proportion with two given numbers.
I go forward likewise and examine whether,
when the numbers 3 and 24 were given, it
would have been equally easy to determine
one of the two intermediate proportionals, viz.
6 and 12. But here still another sort of difficulty
arises more involved than the previous
ones, for on this occasion we have to attend
not to one or two things only but to three, in
order to discover the fourth. We may go still
further and inquire whether if only 3 and 48
had been given it would have been still more
difficult to discover one of the three mean proportionals,
viz. 6,12, and 24. At the first blush
this indeed appears to be so; but immediately
afterwards it comes to mind that this difficulty
can be split up and lessened, if first of all we
ask only for the mean proportional between 3
and 48, viz. 12, and then seek for the other
mean proportional between 3 and 12, viz. 6,
and the other between 12 and 48, viz. 24. Thus,
we have reduced the problem to the difficulty
of the second type shown above.
These illustrations further lead me to note
that the quest for knowledge about the same
thing can traverse different routes, the one much
more difficult and obscure than the other. Thus,
to find these four continued proportionals, 3, 6,
12, and 24, if two consecutive numbers be assumed,
e.g. 3 and 6, or 6 and 12, or 12 and 24,
in order that we may discover the others, our
task will be easy. In this case we shall say that
the proposition to be discovered is directly examined.
But if the two numbers given are alternates,
like 3 and 12, or 6 and 24, which are
to lead us to the discovery of the others, then
we shall call this an indirect investigation of
the first mode. Likewise, if we are given two
extremes like 3 and 24, in order to find out
from these the intermediates 6 and 12, the investigation
will be indirect and of the second
mode. Thus I should be able to proceed further
and deduce many other results from this example
; but these will be sufficient, if the reader
follows my meaning when I say that a proposition
is directly deduced, or indirectly, and will
reflect that from a knowledge of each of these
matters that are simplest and primary, much
may be discovered in other sciences by those
who bring to them attentive thought and a
power of sagacious analysis.
RULE VII
If we wish our science to be complete, those matters
which promote the end we have in view must
one and all be scrutinized by a movement of
thought which is continuous and nowhere interrupted;
they must also be included in an enumeration
which is both adequate and methodical.
IT is necessary to obey the injunctions of
this rule if we hope to gain admission among
the certain truths for those which, we have declared
above, are not immediate deductions
from primary and self-evident principles. For
this deduction frequently involves such a long
series of transitions from ground to consequent
that when we come to the conclusion we have
difficulty in recalling the whole of the route by
which we have arrived at it. This is why I say
that there must be a continuous movement of
thought to make good this weakness of the
memory. Thus, e.g. if I have first found out by
separate mental operations what the relation
is between the magnitudes A and B, then what
between B and C, between C and D, and finally
between D and E, that does not entail my seeing
what the relation is between A and E, nor
can the truths previously learnt give me a precise
knowledge of it unless I recall them all. To
remedy this I would run them over from time
to time, keeping the imagination moving continuously
in such a way that while it is intuitively
perceiving each fact it simultaneously
passes on to the next; and this I would do until
I had learned to pass from the first to the last
so quickly, that no stage in the process was
left to the care of the memory, but I seemed to
have the whole in intuition before me at the
same time. This method will both relieve the
memory, diminish the sluggishness of our
thinking, and definitely enlarge our mental
capacity.
But we must add that this movement should
nowhere be interrupted. Often people who attempt
to deduce a conclusion too quickly and
from remote principles do not trace the whole
chain of intermediate conclusions with sufficient
accuracy to prevent them from passing
over many steps without due consideration.
But it is certain that wherever the smallest
link is left out the chain is broken and the
whole of the certainty of the conclusion falls to
the ground.
Here we maintain that an enumeration [of
the steps in a proof] is required as well, if we
wish to make our science complete. For resolving
most problems other precepts are profitable,
but enumeration alone will secure our
always passing a true and certain judgment on
whatsoever engages our attention; by means
of it nothing at all will escape us, but we shall
evidently have some knowledge of every step.
This enumeration or induction is thus a review
or inventory of all those matters that
have a bearing on the problem raised, which
is so thorough and accurate that by its means
we can clearly and with confidence conclude
that we have omitted nothing by mistake.
Consequently as often as we have employed
it, if the problem defies us, we shall at least be
wiser in this respect, viz. that we are quite certain
that we know of no way of resolving it. If
it chances, as often it does, that we have been
able to scan all the routes leading to it which
lie open to the human intelligence, we shall be
entitled boldly to assert that the solution of
the problem lies outside the reach of human
knowledge.
Furthermore, we must note that by adequate
enumeration or induction is only meant that
method by which we may attain surer conclusions
than by any other type of proof, with the
exception of simple intuition. But when the
knowledge of some matter cannot be reduced
to this, we must cast aside all syllogistic fetters
and employ induction, the only method left us, but one in which all confidence should be reposed. For whenever single facts have
ben immediately deduced the one from the other, they have been already reduced, if the inference was evident, to a true intuition. But if we infer
any single thing from various and disconnected facts, often our intellectual capacity is not so great as to be able to embrace
them all in a single intuition; in which case our mind should be content with the certitude attaching to this operation. It is in precisely
similar fashion that though we cannot with one single gaze distinguish all the links of a lengthy chain, yet if we have seen the connection of each with its neighbour, we shall be entitled to say that we have seen how the first is connected with the last.
I have declared that this operation ought to
be adequate because it is often in danger of
Mire defective and consequently exposed to
Tor. For sometimes, even though in our enumeration
we scrutinize many facts which are
highly evident, yet if we omit the smallest step
the chain is broken and the whole of the certitade
of the conclusion falls to the ground. Sometimes
also, even though all the facts are included
in an accurate enumeration, the single
steps are not distinguished from one another,
and our knowledge of them all is thus only
confused.
Further, while now the enumeration ought
be complete, now distinct, there are times
when it need have neither of these characters;
it was for this reason that I said only that it
should be adequate. For if I want to prove by
enumeration how many genera there are of
corporeal things, or of those that in any way
fa11 under the senses, I shall not assert that
they are just so many and no more, unless I
previously have become aware that I have induded
them all in my enumeration, and have
distinguished them each separately from all
the others. But if in the same way I wish to
prove that the rational soul is not corporeal, I
do not need a complete enumeration; it will be
sufficient to include all bodies in certain collections
in such a way as to be able to demonstrate
that the rational soul has nothing to do
with any of these. If, finally, I wish to show by
enumeration that the area of a circle is greater
than the area of all other figures whose perimeter
is equal, there is no need for me to call
in review all other figures; it is enough to demonstrate
this of certain others in particular,
in order to get thence by induction the same
conclusion about all the others.
I added also that the enumeration ought to
be methodical. This is both because we have
no more serviceable remedy for the defects
already instanced, than to scan all things in an
orderly manner; and also because it often
happens that if each single matter which concerns
the quest in hand were to be investigated
separately, no man's life would be long enough
for the purpose, whether because they are far
too many, or because it would chance that the
same things had to be repeated too often. But
if all these facts are arranged in the best order,
they will for the most part be reduced to determinate
classes, out of which it will be sufficient
to take one example for exact inspection,
or some one feature in a single case, or certain
things rather than others, or at least we shall
never have to waste our time in traversing the
same ground twice. The advantage of this
course is so great that often many particulars
can, owing to a well devised arrangement, be
gone over in a short space of time and with
little trouble, though at first view the matter
looked immense.
But this order which we employ in our enumerations
can for the most part be varied and
depends upon each man's judgment. For this
reason, if we would elaborate it in our thought
with greater penetration, we must remember
what was said in our fifth proposition. There
are also many of the trivial things of man's
devising, in the discovery of which the whole
method lies in the disposal of this order. Thus
if you wish to construct a perfect anagram by
the transposition of the letters of a name, there
is no need to pass from the easy to the difficult,
nor to distinguish absolute from relative. Here
there is no place for these operations; it will be
sufficient to adopt an order to be followed in
the transpositions of the letters which we are
to examine, such that the same arrangements
are never handled twice over. The total number
of transpositions should, e.g. be split up
into definite classes, so that it may immediately
appear in which there is the best hope of finding
what is sought. In this way the task is often
not tedious but merely child's play.
However, these three propositions should
not be separated, because for the most part we
have to think of them together, and all equally
tend towards the perfecting of our method.
There was no great reason for treating one before
the other, and we have expounded them
but briefly here. The reason for this is that in
the rest of the treatise we have practically
nothing else left for consideration. Therefore,
we shall then exhibit in detail what here we
have brought together in a general way.
RULE VIII
If in the matters to be examined we come to a
step in the series of which our understanding is
not sufficiently well able to have an intuitive cognition,
we must stop short there. We must make
no attempt to examine what follows; thus we shall
spare ourselves superfluous labour.
THE THREE preceding rules prescribe and explain
the order to be followed. The present
rule, on the other hand, shows when it is wholly
necessary and when it is merely useful. Thus
it is necessary to examine whatever constitutes
a single step in that series, by which we pass
from relative to absolute, or conversely, before
discussing what follows from it. But if, as often
happens, many things pertain to the same
step, though it is indeed-always profitable to
review them in order, in this case we are not
forced to apply our method of observation so
strictly and rigidly. Frequently it is permissible
to proceed farther, even though we have
not clear knowledge of all the facts it involves,
but know only a few or a single one of them.
This rule is a necessary consequence of the
reasons brought forward in support of the
second. But it must not be thought that the
present rule contributes nothing fresh towards
the advancement of learning, though it seems
only to bid us refrain from further discussion,
and apparently does not unfold any truth. For
beginners, indeed, it has no further value than
to teach them how not to waste time, and it
employs nearly the same arguments in doing
so as Rule II. But it shows those who have perfectly
mastered the seven preceding maxims,
how in the pursuit of any science so to satisfy
themselves as not to desire anything further.
For the man who faithfully complies with the
former rules in the solution of any difficulty,
and yet by the present rule is bidden desist at
a certain point, will then know for certainty
that no amount of application will enable him
to attain to the knowledge desired, and that
not owing to a defect in his intelligence, but
because the nature of the problem itself, or the
fact that he is human, prevents him. But this
knowledge is not the less science than that
which reveals the nature of the thing itself; in
fact he would seem to have some mental defect
who should extend his curiosity farther.
But what we have been saying must be illustrated
by one or two examples. If, for example,
one who studies only Mathematics were
to seek to find that curve which in dioptrics is
called the anaclastic, that from which parallel
rays are so refracted that after the refraction
they all meet in one point,—it will be easy to
see, by applying Rules V and VI, that the determination
of this line depends upon the relation
which the angles of refraction bear to the
angles of incidence. But because he is unable
to discover this, since it is a matter not of
Mathematics but of Physics, he is here forced
to pause at the threshold. Nor will it avail him
to try and learn this from the Philosophers or
to gather it from experience; for this would be
to break Rule III. Furthermore, this proposition
is both composite and relative; but in the
proper place we shall showthat experience is unambiguous
only when dealing with the wholly
simple and absolute. Again, it will be vain for
him to assume some relation or other as being
that which prevails between such angles, and
conjecture that this is the truest to fact; for in
that case he would be on the track not of the
anaclastic, but merely of that curve which
could be deduced from his assumption.
If, however, a man who does not confine his
studies to Mathematics, but, in accordance
with the first rule, tries to discover the truth
on all points, meets with the same difficulty,
he will find in addition that this ratio between
the angles of incidence and of refraction depends
upon changes in their relation produced
by varying the medium. Again these changes
depend upon the manner in which the ray of
light traverses the whole transparent body;
while the knowledge of the way in which the
light thus passes through presupposes a knowledge
of the nature of the action of light, to
understand which finally we must know what
a natural potency is in general, this last being
the most absolute term in the whole series in
question. When, therefore, by a mental intuition
he has clearly comprehended the nature
of this, he will, in compliance with Rule V, proceed
backwards by the same steps. And if
when he comes to the second step he is unable
straightway to determine the nature of light,
he will, in accordance with the seventh rule
enumerate all the other natural potencies, in
order that the knowledge of some other of
them may help him, at least by analogy (of
which more anon), to understand this. This
done, he will ask how the ray traverses the
whole of the transparent body, and will so follow
out the other points methodically, that at
last he will arrive at the anaclastic itself.
Though this has long defied the efforts of many
inquirers, I see no reason why a man who fully
carried out our method should fail to arrive at
a convincing knowledge of the matter.
But let us give the most splendid example of
all. If a man proposes to himself the problem
of examining all the truths for the knowledge
of which human reason suffices—and I think
that this is a task which should be undertaken
once at least in his life by every person who
seriously endeavours to attain equilibrium of
thought—, he will, by the rules given above,
certainly discover that nothing can be known
prior to the understanding, since the knowledge
of all things else depends upon this and
not conversely. Then, when he has clearly
grasped all those things which follow proximately
on the knowledge of the naked understanding,
he will enumerate among other things
whatever instruments of thought we have
other than the understanding; and these are
only two, viz. imagination and sense. He will
therefore devote all his energies to the distinguishing
and examining of these three modes
of cognition, and seeing that in the strict sense
truth and falsity can be a matter of the understanding
alone, though often it derives its origin
from the other two faculties, he will attend
carefully to every source of deception in order
that he may be on his guard. He will also enumerate
exactly all the ways leading to truth
which lie open to us, in order that he may follow
the right way. They are not so many that
they cannot all be easily discovered and embraced
in an adequate enumeration. And
though this will seem marvellous and incredible
to the inexpert, as soon as in each matter
he has distinguished those cognitions which
only fill and embellish the memory, from those
which cause one to be deemed really more instructed,
which it will be easy for him to
do ...; he will feel assured that any absence
of further knowledge is not due to lack of intelligence
or of skill, and that nothing at all
can be known by anyone else which he is not
capable of knowing, provided only that he
gives to it his utmost mental application. And
though many problems may present themselves,
from the solution of which this rule prohibits
him, yet because he will clearly perceive
that they pass the limits of human intelligence,
he will deem that he is not the more ignorant
on that account; rather, if he is reasonable,
this very knowledge, that the solution can be
discovered by no one, will abundantly satisfy
his curiosity.
But lest we should always be uncertain as to
the powers of the mind, and in order that we
may not labour wrongly and at random before
we set ourselves to think out things in detail,
we ought once in our life to inquire diligently
what the thoughts are of which the human
mind is capable. In order the better to attain
this end we ought, when two sets of inquiries
are equally simple, to choose the more useful.
This method of ours resembles indeed those
devices employed by the mechanical crafts,
which do not need the aid of anything outside
of them, but themselves supply the directions
for making their own instruments. Thus if a
man wished to practise any one of them, e.g.
the craft of a smith, and were destitute of all
instruments, be would be forced to use at first
a hard stone or a rough lump of iron as an anvil,
take a piece of rock in place of a hammer,
make pieces of wood serve as tongs, and provide
himself with other such tools as necessity
required. Thus equipped, he would not then at
once attempt to forge swords or helmets or any
manufactured article of iron for others to use.
He would first of all fashion hammer, anvil,
tongs, and the other tools useful for himself.
This example teaches us that, since thus at the
outset we have been able to discover only some
rough precepts, apparently the innate possession
of our mind, rather than the product of
technical skill, we should not forthwith attempt
to settle the controversies of Philosophers,
or solve the puzzles of the Mathematicians,
by their help. We must first employ
them for searching out with our utmost attention
all the other things that are more urgently
required in the investigation of truth. And this
since there is no reason why it should appear
more difficult to discover these than any of the
answers which the problems propounded by
Geometry or Physics or the other sciences are
wont to demand.
Now no more useful inquiry can be proposed
than that which seeks to determine the nature
and the scope of human knowledge. This is
why we state this very problem succinctly in
the single question, which we deem should be
answered at the very outset with the aid of the
rules which we have already laid down. This
investigation should be undertaken once at
least in his life by anyone who has the slightest
regard for truth, since in pursuing it the true
instruments of knowledge and the whole method
of inquiry come to light. But nothing
seems to me more futile than the conduct of
those who boldly dispute about the secrets of
nature, the influence of the heavens on these
lower regions, the predicting of future events
and similar matters, as many do, without yet
having ever asked even whether human reason
is adequate to the solution of these problems.
Neither ought it to seem such a toilsome and
difficult matter to define the limits of that understanding
of which we are directly aware as
being with us, when we often have no hesitation
in' passing judgment even on things that
are without us and quite foreign to us. Neither
is it such an immense task to attempt to grasp
in thought all the objects comprised within
this whole of things, in order to discover how
they singly fall under our mental scrutiny. For
nothing can prove to be so complex or so vague
as to defeat the efforts of the method of enumeration
above described, directed towards
restraining it within certain limits or arranging
it under certain categories. But to put this to
the test in the matter of the question above
propounded, we first of all divide the whole
problem relative to it into two parts; for it
ought either to relate to us who are capable of
knowledge, or to the things themselves which
can be known: and these two factors we discuss
separately.
In ourselves we notice that while it is the
understanding alone which is capable of knowing,
it yet is either helped or hindered by three
other faculties, namely imagination, sense and
memory. We must therefore examine these
faculties in order, with a view to finding out
where each may prove to be an impediment,
so that we may be on our guard; or where it
may profit us, so that we may use to the full
the resources of these powers. This first part of
our problem will accordingly be discussed with
the aid of a sufficient enumeration, as will be
shown in the succeeding proposition.
We come secondly to the things themselves
which must be considered only in so far as they
are the objects of the understanding. From
this point of view we divide them into the
class (1) of those whose nature is of the extremest
simplicity and (2) of the complex and
composite. Simple natures must be either spiritual
or corporeal or at once spiritual and corporeal.
Finally, among the composites there are
some which the understanding realises to be
complex before it judges that it can determine
anything about them; but there are also others
which it itself puts together. All these matters
will be expounded at greater length in the
twelfth proposition, where it will be shown
that there can be no falsity save in the last
class—that of the compounds made by the understanding
itself. This is why we further subdivide
these into the class of those which are
deducible from natures which are of the maximum
simplicity and are known per se, of which
we shall treat in the whole of the succeeding
book; and into those which presuppose the
existence of others which the facts themselves
show us to be composite. To the exposition of
these we destine the whole of the third book.
But we shall indeed attempt in the whole of
this treatise to follow so accurately the paths
which conduct men to the knowledge of the
truth, and to make them so easy, that anyone
who has perfectly learned the whole of this
method, however moderate may be his talent,
may see that no avenue to the truth is closed
to him from which everyone else is not also excluded,
and that his ignorance is due neither to
a deficiency in his capacity nor to his method
of procedure. But as often as he applies his
mind to the understanding of some matter, he
will either be entirely successful, or he will
realise that success depends upon a certain experiment
which he is unable to perform, and
in that case he will not blame his mental capacity
although he is compelled to stop short
there. Or finally, he may show that the knowledge
desired wholly exceeds the limits of the
human intelligence; and consequently he will
believe that he is none the more ignorant on
that account. For to have discovered this is
knowledge in no less degree than the knowledge
of anything else.
RULE IX
We ought to give the whole of our attention to the
most insignificant and most easily mastered facts,
and remain a long time in contemplation of
them until we are accustomed to behold the truth
clearly and distinctly.
WE HAVE now indicated the two operations
of our understanding, intuition and deduction,
on which alone we have said we must rely in
the acquisition of knowledge. Let us therefore
in this and in the following proposition proceed
to explain how we can render ourselves more
skilful in employing them, and at the same
time cultivate the two principal faculties of the
mind, to wit perspicacity, by viewing single
objects distinctly, and sagacity, by the skilful
deduction of certain facts from others.
Truly we shall learn how to employ our
mental intuition from comparing it with the
way in which we employ our eyes. For he who
attempts to view a multitude of objects with
one and the same glance, sees none of them
distinctly; and similarly the man who is wont
to attend to many things at the same time by
means of a single act of thought is confused in
mind. But just as workmen, who are employed
in very fine and delicate operations and are
accustomed to direct their eyesight attentively
to separate points, by practice have acquired
a capacity for distinguishing objects of
extreme minuteness and subtlety; so likewise
people, who do not allow their thought to be
distracted by various objects at the same time,
but always concentrate it in attending to the
simplest and easiest particulars, are clearheaded.
But it is a common failing of mortals to
deem the more difficult the fairer; and they
often think that they have learned nothing
when they see a very clear and simple cause
for a fact, while at the same time they are lost
in admiration of certain sublime and profound
philosophical explanations, even though these
for the most part are based upon foundations
which no one had adequately surveyed—a
mental disorder which prizes the darkness
higher than the light. But it is notable that
those who have real knowledge discern the
truth with equal facility whether they evolve
it from matter that is simple or that is obscure;
they grasp each fact by an act of thought that
is similar, single, and distinct, after they have
once arrived at the point in question. The
whole of the difference between the apprehension
of the simple and of the obscure lies in the
route taken, which certainly ought to be longer
if it conducts us from our initial and most absolute
principles to a truth that is somewhat
remote.
Everyone ought therefore to accustom himself
to grasp in his thought at the same time
facts that are at once so few and so simple,
that he shall never believe that he has knowledge
of anything which he does not mentally
behold with a distinctness equal to that of the
objects which he knows most distinctly of all.
It is true that some men are born with a much
greater aptitude for such discernment than
others, but the mind can be made much more
expert at such work by art and exercise. But
there is one fact which I should here emphasize
above all others; and that is that everyone
should firmly persuade himself that none of
the sciences, however abstruse, is to be deduced
from lofty and obscure matters, but
that they all proceed only from what is easy
and more readily understood.
For example if I wish to examine whether it
is possible for a natural force to pass at one and
the same moment to a spot at a distance and
yet to traverse the whole space in between, I
shall not begin to study the force of magnetism
or the influence of the stars, not even the speed
of light, in order to discover whether actions
such as these occur instantaneously; for the
solution of this question would be more difficult
than the problem proposed. I should rather
bethink myself of the spatial motions of bodies,
because nothing in the sphere of motion can
be found more obvious to sense than this. I
shall observe that while a stone cannot pass to
another place in one and the same moment,
because it is a body, yet a force similar to that
which moves the stone is communicated exactly
instantaneously if it passes unencumbered
from one object to another. For instance,
if I move one end of a stick of whatever length,
I easily understand that the power by which
that part of the stick is moved necessarily
moves also all its other parts at the same moment,
because then the force passes unencumbered
and is not imprisoned in any body, e.g.
a stone, which bears it along.
In the same way if I wish to understand how
one and the same simple cause can produce
contrary effects at the same time, I shall not
cite the drugs of the doctors which expel certain
humours and retain others; nor shall I romance
about the moon's power of warming
with its light and chilling by means of some
occult power. I shall rather cast my eyes upon
the balance in which the same weight raises
one arm at the same time as it depresses the
other, or take some other familiar instance.
RULE X
In order that it may acquire sagacity the mind
should be exercised in pursuing just those inquiries
of which the solution has already been
found by others; and it ought to traverse in a
systematic way even the most trifling of men's
inventions though those ought to be preferred in
which order is explained or implied.
I CONFESS that my natural disposition is such
that I have always found, not the following of
the arguments of others, but the discovery of
reasons by my own proper efforts, to yield me
the highest intellectual satisfaction. It was
this alone that attracted me, when I was still a
young man, to the study of science. And whenever
any book by its title promised some new
discovery, before I read further I tried whether
I could achieve something similar by means of
some inborn faculty of invention, and I was
careful lest a premature perusal of the book
might deprive me of this harmless pleasure. So
often was I successful that at length I perceived
that I no longer came upon the truth by
proceeding as others commonly do, viz. by
pursuing vague and blind inquiries and relying
more on good fortune than on skill. I saw
that by long experience I had discovered certain
rules which are of no little help in this
inquiry, and which I used afterwards in devising
further rules. Thus it was that I diligently
elaborated the whole of this method
and came to the conclusion that I had followed
that plan of study which was the most fruitful
of all.
But because not all minds are so much inclined
to puzzle things out unaided, this proposition
announces that we ought not immediately
to occupy ourselves with the more
difficult and arduous problems, but first should
discuss those disciplines which are easiest and
simplest, and those above all in which order
most prevails. Such are the arts of the craftsmen
who weave webs and tapestry, or of
women who embroider or use in the same work
threads with infinite modification of texture.
With these are ranked all play with numbers
and everything that belongs to Arithmetic,
and the like. It is wonderful how all these
studies discipline our mental powers, provided
that we do not know the solutions from others,
but invent them ourselves. For since nothing
in these arts remains hidden, and they are
wholly adjusted to the capacity of human cognition,
they reveal to us with the greatest distinctness
innumerable orderly systems, all
different from each other, but none the less
conforming to rule, in the proper observance
of which systems of order consists the whole of
human sagacity.
It was for this reason that we insisted that
method must be employed in studying these
matters; and this in those arts of less importance
consists wholly in the close observation
of the order which is found in the object
studied, whether that be an order existing in
the thing itself, or due to subtle human devising.
Thus if we wish to make out some
writing in which the meaning is disguised by
the use of a cypher, though the order here fails
to present itself, we yet make up an imaginary
one, for the purpose both of testing all the conjectures
we may make about single letters,
words or sentences, and in order to arrange
them so that when we sum them up we shall
be able to tell all the inferences that we can
deduce from them. We must principally beware
of wasting our time in such cases by proceeding
at random and unmethodically; for
even though the solution can often be found
without method, and by lucky people sometimes
quicker, yet such procedure is likely to
enfeeble the faculties and to make people accustomed
to the trifling and the childish, so
that for the future their minds will stick on the
surface of things, incapable of penetrating beyond
it. But meanwhile we must not fall into
the error of those who, having devoted themselves
solely to what is lofty and serious, find
that after many years of toil they have acquired,
not the profound knowledge they
hoped for, but only mental confusion. Hence
we must give ourselves practice first in those
easier disciplines, but methodically, so that by
open and familiar ways we may ceaselessly accustom
ourselves to penetrate as easily as
though we were at play into the very heart of
these subjects. For by this means we shall
afterwards gradually feel (and in a space of
time shorter than we could at all hope for) that
we are in a position with equal facility to deduce
from evident first principles many propositions
which at first sight are highly intricate
and difficult.
It may perhaps strike some with surprise
that here, where we are discussing how to improve
our power of deducing one truth from
another, we have omitted all the precepts of
the dialecticians, by which they think to control
the human reason. They prescribe certain
formulae of argument, which lead to a conclusion
with such necessity that, if the reason
commits itself to their trust, even though it
slackens its interest and no longer pays a heedful
and close attention to the very proposition
inferred, it can nevertheless at the same time
come to a sure conclusion by virtue of the form
of the argument alone. Exactly so; the fact is
that frequently we notice that often the truth
escapes away out of these imprisoning bonds,
while the people themselves who have used
them in order to capture it remain entangled
in them. Other people are not so frequently
entrapped; and it is a matter of experience that
the most ingenious sophisms hardly ever impose
on anyone who uses his unaided reason, while
they are wont to deceive the sophists themselves.
Wherefore as we wish here to be particularly
careful lest our reason should go on holiday
while we are examining the truth of any matter,
we reject those formulae as being opposed
to our project, and look out rather for all the
aids by which our thought may be kept attentive,
as will be shown in the sequel. But, to say
a few words more, that it may appear still
more evident that this style of argument contributes
nothing at all to the discovery of the
truth, we must note that the Dialecticians are
unable to devise any syllogism which has a
true conclusion, unless they have first secured
the material out of which to construct it, i.e.
unless they have already ascertained the very
truth which is deduced in that syllogism.
Whence it is clear that from a formula of this
kind they can gather nothing that is new, and
hence the ordinary Dialectic is quite valueless
for those who desire to investigate the truth of
things. Its only possible use is to serve to explain
at times more easily to others the truths we
have already ascertained; hence it should be
transferred from Philosophy to Rhetoric.
RULE XI
If, after we have recognised intuitively a number
of simple truths, we wish to draw any inference
from them, it is useful to run them over in a continuous
and uninterrupted act of thought, to reflect
upon their relations to one another, and to
grasp together distinctly a number of these propositions
so far as is possible at the same time. For
this is a way of making our knowledge much
more certain, and of greatly increasing the -power
of the mind.
HERE we have an opportunity of expounding
more clearly what has been already said of
mental intuition in the third and seventh rules.
In one passage1 we opposed it to deduction,
while in the other we distinguished it from
enumeration only, which we defined as an inference
drawn from many and diverse things2.
But the simple deduction of one thing from another,
we said in the same passage3, was effected
by intuition.
It was necessary to do this, because two
things are requisite for mental intuition. Firstly,
the proposition intuited must be clear and
distinct; secondly, it must be grasped in its
totality at the same time and not successively.
As for deduction, if we are thinking of how
the process works, as we were in Rule III,
it appears not to occur all at the same tune,
but involves a sort of movement on the part of
our mind when it infers one thing from another.
We were justified therefore in distinguishing
deduction in that rule-from intuition. But if we
wish to consider deduction as an accomplished
fact, as we did in what we said relatively to the
seventh rule, then it no longer designates a
movement, but rather the completion of a
movement, and therefore we suppose that it is
presented to us by intuition when it is simple
and clear, but not when it is complex and involved.
When this is the case we give it the
name of enumeration or induction, because it
cannot then be grasped as a whole at the same
time by the mind, and its certainty depends to
some extent on the memory, in which our
judgments about the various matters enumerated
must be retained, if from their assemblage
a single fact is to be inferred.
All these distinctions had to be made if we
were to elucidate this rule. We treated of mental
intuition solely in Rule IX; the tenth dealt
with enumeration alone; but now the present
rule explains how these two operations aid and
complete each other. In doing so they seem to
grow into a single process by virtue of a sort of
motion of thought which has an attentive and
vision-like knowledge of one fact and yet can
pass at the very same moment to another.
Xow to this co-operation we assign a twofold
advantage. Firstly, it promotes a more
certain knowledge of the conclusion with which
we are concerned, and secondly, it makes the
mind readier to discover fresh truths. In fact
the memory, on which we have said depends
the certainty of the conclusions which embrace
more than we can grasp in a single act of intuition,
though weak and liable to fail us, can be
renewed and made stronger by this continuous
and constantly repeated process of thought.
Thus if diverse mental acts have led me to
know what, is the relation between a first and a
second magnitude, next between the second
and a third, then between the third and a
fourth, and finally the fourth and a fifth, that
need not lead me to see what is the relation
between the first and the fifth, nor can I deduce
it from what I already know, unless I remember
all the other relations. Hence what I
have to do is to run over them all repeatedly in
my mind, until I pass so quickly from the first
to the last that practically no step is left to the
memory, and I seem to view the whole all at
the same time.
Everyone must see that this plan does much
to counteract the slowness of the mind and to
enlarge its capacity. But in addition we must
note that the greatest advantage of this rule
consists in the fact that, by reflecting on the
mutual dependence of two propositions, we acquire
the habit of distinguishing at a glance
what is more or less relative, and what the
steps are by which a relative fact is related to
something absolute. For example, if I run over
a number of magnitudes that are in continued
proportion, I shall reflect upon all the following
facts: viz. that the mental act is entirely
similar—and not easier in the one case, more
difficult in another—by which I grasp the relation
between the first and the second, the second
and third, third and fourth, and so on;
while yet it is more difficult for me to conceive
what the relation of the second is to the first
and to the third at the same time, and much
more difficult still to tell its relation to the first
and fourth, and so on. These considerations
then lead me to see why. if the first and second
alone are given. I can easily find the third and
fourth, and all the others: the reason being
that this process requires only single and distinct
acts of thought. But if only the first and
the third are given, it is not so easy to recognize
the mean, because this can only be accomplished
by means of a mental operation in
which two of the previous acts are involved. If
the first and the fourth magnitudes alone are
given, it is still more difficult to present to ourselves
the two means, because here three acts
of thought come in simultaneously. It would
seem likely as a consequence that it would be
even more difficult to discover the three means
between the first and the fifth. The reason why
this is not so is due to a fresh fact; viz. even
though here four mental acts come together
they can yet be disjoined, since four can be divided
by another number. Thus I can discover
the third by itself from the first and fifth, then
the second from the first and third, and so on.
If one accustoms one's self to reflect on these
and similar problems, as often as a new question
arises, at once one recognizes what produces
its special difficulty, and what is the
simplest method of dealing with all cases; and
to be able to do so is a valuable aid to the discovery
of the truth.
RULE XII
Finally we ought to employ all the aids of understanding,
imagination, sense and memory, first
for the purpose of having a distinct intuition of
simple propositions; partly also in order to compare
the propositions to be proved with those we
know already, so that we may be abk to recognize
their truth; partly also in order to discover the
truths, which should be compared with each other
so that nothing may be left lacking on which human
industry may exercise itself.
THIS rule states the conclusion of all that we
said before, and shows in general outline what
had to be explained in detail, in this wise.
In the matter of cognition of facts two things
alone have to be considered, ourselves who
know and the objects themselves which are to
be known. Within us there are four faculties
only which we can use for this purpose, viz.
understanding, imagination, sense and memory.
The understanding is indeed alone capable
of perceiving the truth, but yet it ought to be
aided by imagination, sense and memory, lest
perchance we omit any expedient that lies
within our power. On the side of the facts to be
known it is enough to examine three things;
first, that which presents itself spontaneously,
secondly, how we learn one thing by means of
another, and thirdly, what (truths) are deduced
from what. This enumeration appears to me to
be complete, and to omit nothing to which our
human powers can apply.
I should have liked therefore to have turned
to the first point and to have explained in this
passage, what the human mind is, what body,
and how it is "informed" by mind; what the
faculties in the complex whole are which serve
the attainment of knowledge, and what the
agency of each is. But this place seems hardly
to give me sufficient room to take in all the
matters which must be premised before the
truth in this subject can become clear to all.
For my desire is in all that I write to assert
nothing controversial unless I have already
stated the very reasons which have brought me
to that conclusion, and by "which I think that
others also may be convinced.
But because at present I am, prevented from
doing this, it will suffice me to explain as briefly
as possible that mode of viewing everything
within us which is directed towards the discovery
of truth, which most promotes my purpose.
You need not believe that the facts are so
unless you like. But what prevents us following
these suppositions, if it appears that they
do no harm to the truth, but only render it all
much clearer? In Geometry you do precisely
the same thing when you make certain assumptions
about a quantity which do not in any
way weaken the force of your arguments,
though often our experience of its nature in
Physics makes us judge of it quite otherwise.
Let us then conceive of the matter as follows:—
all our external senses, in so far as they
are part of the body, and despite the fact that
we direct them towards objects, so manifesting
activity, viz. a movement in space, nevertheless
properly speaking perceive in virtue of
passivity alone, just in the way that wax receives
an impression from a seal. And it should
not be thought that all we mean to assert is an
analogy between the two. We ought to believe
that the way is entirely the same in which the
exterior figure of the sentient body is really
modified by the object, as that in which the
shape of the surface of the wax is altered by the
seal. This has to be admitted not only in the
case of the figure, hardness, roughness, etc. of
a body which we perceive by touch, but even
when we are aware of heat, cold, and the like
qualities. It is likewise with the other senses.
The first opaque structure in the eye receives
the figure impressed upon it by the light with
its various colours; and the first membrane in
the ears, the nose, and the tongue that resists
the further passage of the object, thus also acquires
a new figure from the sound, the odour,
and the savour, as the case may be.
It is exceedingly helpful to conceive all those
matters thus, for nothing falls more readily
under sense than figure, which can be touched
and seen. Moreover that nothing false issues
from this supposition more than from any
other, is proved by the fact that the concept
of figure is so common and simple that it is involved
in every object of sense. Thus whatever
you suppose colour to be, you cannot deny
that it is extended and in consequence possessed
of figure. Is there then any disadvantage,
if, while taking care not to admit any new
entity uselessly, or rashly to imagine that it
exists, and not denying indeed the beliefs of
others concerning colour, but merely abstracting
from every other feature except that it possesses
the nature of figure, we conceive the diversity
existing between white, blue, and red,
etc., as being like the difference between the
following similar figures?
The same argument
applies to all cases; for it is certain that the
infinitude of figures suffices to express all the
differences in sensible things.
Secondly, we must believe that while the external
sense is stimulated by the object, the
figure which is conveyed to it is carried off to
some other part of the body, that part called
the common sense, in the very same instant
and without the passage of any real entity from
one to the other. It is in exactly the same
manner that now when I write I recognize
that at the very moment when the separate
characters are being written down on the
paper, not only is the lower end of the pen
moved, but every motion in that part is simultaneously
shared by the whole pen. All these
diverse motions are traced by the upper end of
the pen likewise in the air, although I do not
conceive of anything real passing from the one
extremity to the other. Now who imagines that
the connection between the different parts of
the human body is slighter than that between
the ends of a pen, and what simpler way of expressing
this could be found?
Thirdly, we must believe that the common
sense has a function like that of a seal, and impresses
on the fancy or imagination, as though
on wax, those very figures and ideas which
come uncontaminated and without bodily admixture
from the external senses. But this fancy
is a genuine part of the body, of sufficient
size to allow its different parts to assume various
figures in distinctness from each other and
to let those parts acquire the practice of retaining
the impressions for some time. In the latter
case we give the faculty the name of memory.
In the fourth place, we must conceive that
the motor force or the nerves themselves derive
their origin from the brain, in which the
fancy is located, and that the fancy moves
them in various ways, just as the external
senses act on the common sense, or the lower
extremity of the pen moves the whole pen. This
example also shows how the fancy can be the cause of many
motions in the nerves, motions of which, however, it does not
have the images stamped upon it, possessing only certain other
images from which these latter follow. Just so the whole pen
does not move exactly in the way in which its lower end
does; nay the greater part seems
to have a motion that is quite different from
and contrary to that of the other. This lets us
understand how all the motions of the other
animals can come about, though we can ascribe
to them no knowledge at all, but only fancy of a
purely corporeal kind. We can explain also how
in ourselves all those operations occur which
we perform without any aid from the reason.
Finally and in the fifth place, we must think
that that power by which we are properly said
to know things, is purely spiritual, and not less
distinct from every part of the body than
blood from bone, or hand from eye. It is a
single agency, whether it receives impressions
from the common sense simultaneously with
the fancy, or applies itself to those that are
preserved in the memory, or forms new ones.
Often the imagination is so beset by these impressions
that it is unable at the same time to
receive ideas from the common sense, or to
transfer them to the motor mechanism in the
way befitting its purely corporeal character. In
all these operations this cognitive power is at
one time passive, at another active, and resembles
now the seal and now the wax. But the
resemblance on this occasion is only one of
analogy, for among corporeal things there is
nothing wholly similar to this faculty. It is one
and the same agency which, when applying itself
along with the imagination to the common
sense, is said to see, touch, etc.; if applying itself
to the imagination alone in so far as that is
endowed with diverse impressions, it is said to
remember; if it turn to the imagination in order
to create fresh impressions, it is said to
imagine or conceive; finally if it act alone it is
said to understand. How this latter function
takes place I shall explain at greater length in
the proper place. Now it is the same faculty
that in correspondence with those various
functions is called either pure understanding,
or imagination, or memory, or sense. It is
properly called mind when it either forms new
ideas in the fancy, or attends to those already
formed. We consider it as capable of the above
various operations, and this distinction between
those terms must in the sequel be borne
in mind. But after having grasped these facts
the attentive reader will gather what help is to
be expected from each particular faculty, and
discover how far human effort can avail to
supplement the deficiencies of our mental
powers.
For, since the understanding can be stimulated
by the imagination, or on the contrary
act on it; and seeing that the imagination can
act on the senses by means of the motor power
applying them to objects, while they on the
contrary can act on it, depicting on it the images
of bodies; considering on the other hand
that the memory, at least that which is corporeal
and similar to that of the brutes, is in no
respect distinct from the imagination; we come
to the sure conclusion that, if the understanding
deal with matters in which there is nothing
corporeal or similar to the corporeal, it cannot
be helped by those faculties, but that, on the
contrary, to prevent their hampering it, the
senses must be banished and the imagination
as far as possible divested of every distinct impression.
But if the understanding proposes to
examine something that can be referred to the
body, we must form the idea of that thing as
distinctly as possible in the imagination; and
in order to effect this with greater ease, the
thing itself which this idea is to represent must
be exhibited to the external senses. Now when
the understanding wishes to have a distinct intuition
of particular facts a multitude of objects
is of no use to it. But if it wishes to deduce
one thing from a number of objects, as often
has to be done, we must banish from the ideas
of the objects presented whatsoever does not
require present attention, in order that the remainder
may be the more readily retained in
memory. In the same way it is not on those
occasions that the objects themselves ought to
be presented to the external senses, but rather
certain compendious abbreviations which.
provided they guard the memory against lapse,
are the handier the shorter they are. Whosoever
observes all these recommendations, will,
in my opinion, omit nothing that relates to the
first part of our rule.
Now we must approach the second part of
our task. That was to distinguish accurately
the notions of simple things from those which
are built up out of them; to see in both cases
where falsity might come in, so that we might
be on our guard and give our attention to those
matters only in which certainty was possible.
But here, as before, we must make certain assumptions
which probably are not agreed on
by all. It matters little, however, though they
are not believed to be more real than those
imaginary circles by means of which Astronomers
describe their phenomena, provided that
you employ them to aid you in discerning in
each particular case what sort of knowledge is
true and what false.
Finally, then, we assert that relatively to
our knowledge single things should be taken in
an order different from that in which we should
regard them when considered in their more real
nature. Thus, for example, if we consider a
body as having ex-tension and figure, we shall
indeed admit that from the point of view of the
thing itself it is one and simple. For we cannot
from that point of view regard it as compounded
of corporeal nature, extension and figure,
since these elements have never existed in isolation
from each other. But relatively to our
understanding we call it a compound constructed
out of these three natures, because we
have thought of them separately before we
were able to judge that all three were found in
one and the same subject. Hence here we shall
treat of things only in relation to our understanding's
awareness of them, and shall call
those only simple, the cognition of which is so
clear and so distinct that they cannot be analysed
by the mind into others more distinctly
known. Such are figure, extension, motion,
etc.; all others we conceive to be in some way
compounded out of these. This principle must
be taken so universally as not even to leave out
those objects which we sometimes obtain by
abstraction from the simple natures themselves.
This we do, for example, when we say
that figure is the limit of an extended thing,
conceiving by the term limit something more
universal than by the term figure, since we can
talk of a limit of duration, a limit of motion,
and so on. But our contention is right, for then,
even though we find the meaning of limit by
abstracting it from figure, nevertheless it
should not for that reason seem simpler than
figure. Rather, since it is predicated of other
things, as for example of the extreme bounds
of a space of time or of a motion, etc., things
which are wholly different from figure, it must
be abstracted from those natures also; consequently
it is something compounded out of a
number of natures wholly diverse, of which it
can be only ambiguously predicated.
Our second assertion is that those things
which relatively to our understanding are
called simple, are either purely intellectual or
purely material, or else common both to intellect
and to matter. Those are purely intellectual
which our understanding apprehends by
means of a certain inborn light, and without
the aid of any corporeal image. That a number
of such things exist is certain; and it is impossible
to construct any corporeal idea which
shall represent to us what the act of knowing
is, what doubt is, what ignorance, and likewise
what the action of the will is which it is possible
to term volition, and so with other things.
Yet we have a genuine knowledge of all these
things, and know them so easily that in order
to recognize them it is enough to be endowed
with reason. Those things are purely material
which we discern only in bodies; e.g. figure,
extension, motion, etc. Finally those must be
styled common which are ascribed now to corporeal
things, now to spirits, without distinction.
Such are existence, unity, duration and
the like. To this group also we must ascribe
those common notions which are, as it were,
bonds for connecting together the other simple
natures, and on whose evidence all the inferences
which we obtain by reasoning depend.
The following are examples:—things that are
the same as a third thing are the same as one
another. So too:—things which do not bear the
same relation to a third thing, have some diversity
from each other, etc. As a matter of
fact these common notions can be discerned by
the understanding either unaided or when it is
aware of the images of material things.
But among these simple natures we must
rank the privative and negative terms corresponding
to them hi so far as our intelligence
grasps them. For it is quite as genuinely an act
of knowledge by which I am intuitively aware
of what nothing is, or an instant, or rest, as
that by which I know what existence is, or
lapse of time, or motion. This way of viewing
the matter will be helpful in enabling us henceforth
to say that all the rest of what we know
is formed by composition out of these simple
natures. Thus, for example, if I pronounce the
judgment that some figure is not moving, I
shall say that in a certain sense my idea is a
complex of figure and rest; and so in other
cases.
Thirdly, we assert that all these simple natures
are known per se and arc wholly free from
falsity. It will be easy to show this, provided
we distinguish that faculty of our understanding
by which it has intuitive awareness of
things and knows them, from that by which it
judges, making use of affirmation and denial.
For we may imagine ourselves to be ignorant
of things which we really know, for example on
such occasions as when we believe that in such
things, over and above what we have present
to us or attain to by thinking, there is something
else hidden from us, and when this belief
of ours is false. Whence it is evident that we
are in error if we judge that any one of these
simple natures is not completely known by us.
For if our mind attains to the least acquaintance
with it, as must be the case, since we are
assumed to pass some judgment on it, this fact
alone makes us infer that we know it completely.
For otherwise it could not be said to be
simple, but must be complex—a compound of
that which is present in our perception of it,
and that of which we think we are ignorant.
In the fourth place, we point out that the
union of these things one with another is either
necessary or contingent. It is necessary when
one is so implied in the concept of another in a
confused sort of way that we cannot conceive
either distinctly, if our thought assigns to
them separateness from each other. Thus figure
is conjoined with extension, motion with
duration or time, and so on, because it is impossible
to conceive of a figure that has no extension,
nor of a motion that has no duration.
Thus likewise if I say "four and three are
seven," this union is necessary. For we do not
conceive the number seven distinctly unless we
include in it the numbers three and four in
some confused way. In the same way whatever
is demonstrated of figures or numbers is necessarily
united with that of which it is affirmed.
Further, this necessity is not restricted to the
field of sensible matters alone. The conclusion
is necessary also in such a case—If Socrates
says he doubts everything, it follows necessarily
that he knows this at least—that he doubts.
Likewise he knows that something can be either
true or false, and so on, for all those consequences
necessarily attach to the nature of
doubt. The union, however, is contingent in
those cases where the things are conjoined by
no inseparable bond. Thus when we say a body
is animate, a man is clothed, etc. Likewise
many things are often ne<^essarily united with
one another, though most people, not noticing
what their true relation is, reckon them among
those that are contingently connected. As example,
I give the following propositions:—"I
exist,therefore God exists": also "I know, therefore
I have a mind distinct from my body,"etc.
Finally, we must note that very many necessary
propositions become contingent when
converted. Thus, though from the fact that I
exist I may infallibly conclude that God exists,
it is not for that reason allowable to affirm that
because God exists I also exist.
Fifthly, we remark that no knowledge is at
any time possible of anything beyond those
simple natures and what may be called their
intermixture or combination with each other.
Indeed it is often easier to be aware of several
of them in union with each other, than to separate
one of them from the others. For, to illustrate,
I am able to know what a triangle is,
though I have never thought that in that
knowledge was contained the knowledge of an
angle, a line, the number three, figure, extension,
etc. But that does not prevent me from
saying that the nature of the triangle is composed
of all these natures, and that they are
better known than the triangle since they are
the elements which we comprehend in it. It is
possible also that in the triangle many other
features are involved which escape our notice,
such as the magnitude of the angles, which are
equal to two right angles, and the innumerable
relations which exist between the sides and the
angles, or the size of the area, etc.
Sixthly, we say that those natures which we
call composite are known by us, either because
experience shows us what they are, or because
we ourselves are responsible for their composition.
Matter of experience consists of what we
perceive by sense, what we hear from the lips
of others, and generally whatever reaches our
understanding either from external sources or
from that contemplation which our mind directs
backwards on itself. Here it must be noted
that no direct experience can ever deceive the
understanding if it restrict its attention accurately
to the object presented to it, just as it is
given to it either at firsthand or by means of an
image; and if it moreover refrain from judging
that the imagination faithfully reports the objects
of the senses, or that the senses take on
the true forms of things, or in fine that external
things always are as they appear to be; for in
all these judgments we are exposed to error.
This happens, for example, when we believe as
fact what is merely a story that someone has
told us; or when one who is ill with jaundice
judges everything-to be yellow because his eye
is tinged with yellow. So finally, too, when the
imagination is diseased, as in cases of melancholia,
and a man thinks that his own disorderly
fancies represent real things. But the understanding
of a wise man will not be deceived by
these fancies, since he will judge that whatever
comes to him from his imagination is really depicted
in it, but yet will never assert that the
object has passed complete and without any
alteration from the external world to his senses,
and from his senses to his imagination, unless
he has some previous ground for believing this.
Moreover we ourselves are responsible for the
composition of the things present to our understanding
when we believe that there is something
in them which our mind never experiences
when exercising direct perception. Thus
if a man suffering from jaundice persuades
himself that the things he sees are yellow, this
thought of his will be composite, consisting
partly of what his imagination represents to
him, and partly of what he assumes on his own
account, namely that the colour looks yellow
not owing to the defect in his eye, but because
the things he sees really are yellow. Whence
the conclusion comes that we can go wrong
only when the things we believe are in some
way compounded by ourselves.
Seventhly, this compounding can come about
in other ways, namely by impulse, by conjecture,
or by deduction. Impulse sways the formation of judgments about things on the part
of those whom their own initiative constrains
to believe something, though they can assign
no reason for their belief, but are merely determined either by some higher Power, or by
their own free will, or by their fanciful disposition. The first cause is never a source of error,
the second rarely, the third almost always. But a consideration of the first does not concern
us here because it does not fall within the
province of human skill. The working of conjecture
is shown, for example, in this: water
which is at a greater distance from the centre
of the globe than earth, is likewise less dense
substance, and likewise the air which is above
the water, is still rarer; hence we hazard the
guess that above the air nothing exists but a
very pure aether, which is much rarer than air
itself. Moreover nothing that we construct in
this way really deceives us, if we merely judge
it to be probable and never affirm it to be true;
in fact it makes us better instructed.
Deduction is thus left to us as the only
means of putting things together so as to be
sure of their truth. Yet in it, too, there may be
many defects. Thus if, in this space which is
full of air, there is nothing to be perceived
either by sight, touch, or any other sense, we
conclude that the space is empty, we are in
error, and our synthesis of the nature of a
vacuum with that of this space is wrong. This
is the result as often as we judge that we can
deduce anything universal and necessary from
a particular or contingent fact. But it is within
our power to avoid this error, if, for example,
we never interconnect any objects unless we are
directly aware that the conjunction of the one
with the other is wholly necessary. Thus we are
justified if we deduce that nothing can have
figure which has not extension, from the fact that
figure and extension are necessarily conjoined.
From all these considerations we conclude
firstly—that we have shown distinctly and, as
we judge, by an adequate enumeration, what
we were originally able to express only confusedly
and in a rough and ready way. This
was that mankind has no road towards certain
knowledge open to it, save those of self-evident
intuition and necessary deduction; further,
that we have shown what those simple natures
are of which we spoke in the eighth proposition.
It is also quite clear that this mental vision
extends both to all those simple natures,
and to the knowledge of the necessary connections
between them, and finally to everything
else which the understanding accurately experiences
either at first hand or in the imagination.
Deduction, however, will be further treated
in what follows.
Our second conclusion is that in order to
know these simple natures no pains need be
taken, because they are of themselves sufficiently
well known. Application comes in only
in isolating them from each other and scrutinizing
them separately with steadfast mental
gaze. There is no one whose intelligence is so
dull as not to perceive that when he is seated
he in some way differs from what he is when
standing. But not everyone separates with
equal distinctness the nature of position from
the other elements contained in the cognition
in question, or is able to assert that in this case
nothing alters save the position. Now it is not
without reason that we call attention to the
above doctrine; for the learned have a way of
being so clever as to contrive to render themselves
blind to things that are in their own nature
evident, and known by the simplest peasant.
This happens when they try to explain by
something more evident those things that are
self-evident. For what they do is either to explain
something else, or nothing at all. Who,
for instance, does not perfectly see what that
is, whatsoever it may be, in respect of which
alteration occurs when we change position?
But is there anyone who would grasp that very
thing when he was told that place is the surface
of the body surrounding us?1 This would be
strange seeing that that surface can change
though I stay still and do not change my place,
or that, on the contrary, it can so move along
with me that, although it continues to surround
me, I am nevertheless no longer in the
same place. Do not these people really seem to
use magic words which have a hidden force
that eludes the grasp of human apprehension?
They define motion, a fact with which everyone
is quite familiar, as the actualization of
what exists in potentiality, in so far as it is potential!
Now who understands these words?
And who at the same time does not know what
motion is? Will not everyone admit that those
philosophers have been trying to find a knot
in a bulrush? We must therefore maintain that
no definitions are to be used in explaining
things of this kind lest we should take what is
complex in place of what is simple. We must
be content to isolate them from each other,
and to give them, each of us, our individual
attention, studying them with that degree of
mental illumination which each of us possesses.
Our third conclusion is that the whole of human
knowledge consists in a distinct perception
of the way in which those simple natures
combine in order to build up other objects. It
is important to note this; because whenever
some difficulty is brought forward for examination,
almost everyone is brought to a standstill
at the very outset, being in doubt as to the
nature of the notions he ought to call to mind,
and believing that he has to search for some
new kind of fact previously unknown to him.
Thus, if the question is, "what is the nature of
the magnet?" people like that at once prognosticate
difficulty and toil in the inquiry, and
dismissing from mind every well-known fact,
fasten on whatsoever is most difficult, vaguely
hoping that by ranging over the fruitless field
where multifarious causes lie, they will find
something fresh. But he who reflects that
there can be nothing to know in the magnet
which does not consist of certain simple natures
evident in themselves, will nave no doubt
how to proceed. He will first collect all the observations
with which experience can supply
him about this stone, and from these he will
next try to deduce the character of that intermixture
of simple natures which is necessary
to produce all those effects which he has seen
to take place in connection with the magnet.
This achieved, he can boldly assert that he hns
discovered the real nature of the magnet in so
far as human intelligence and the given experimental
observations can supply him with this
knowledge.
Finally, it follows fourthly from what has
been said that we must not fancy that one kind
of knowledge is more obscure than another,
since all knowledge is of the same nature
throughout, and consists solely in combining
what is self-evident. This is a fact recognized
by very few. People have their minds already
occupied by the contrary opinion, and the
more bold among them, indeed, allow themselves
to uphold their private conjectures as
though they were sound demonstrations, and
in matters of which they are wholly ignorant
feel premonitions of the vision of truths which
seem to present themselves through a cloud.
These they have no hesitation in propounding,
attaching to their concepts certain words by
means of which they are wont to carry on long
and reasoned out discussions, but which in
reality neither they nor their audience understand.
On the other hand more diffident people
often refrain from many investigations that
are quite easy and are in the first degree necessary
to life, merely because they think themselves
unequal to the task. They believe that
these matters can be discovered by others who
are endowed with better mental faculties, and
embrace the opinion of those in whose authority
they have most confidence.
We assert fifthly that by deduction we can
get only things from words, cause from effect,
or effect from cause, like from like, or parts or
the whole itself from the parts....
For the rest, in order that there may be no
want of coherence in our series of precepts, we
divide the whole matter of knowledge into
simple propositions and "questions." (Quotation marks have been employed
wherever it is important to remember Descartes'
special technical use of this term.) In connection
with simple propositions the only precepts
we give are those which prepare our cognitive
faculties for fixing distinctly before them
any objects, whatsoever they are, and scrutinizing
them with keen intelligence, since propositions
of this type do not arise as the result of
inquiry, but present themselves to us spontaneously.
This part of our task we have undertaken
in the first twelve rules, in which, we
believe, we have displayed everything which,
in our opinion, can facilitate the exercise of our
reason. But as to "questions" some of them
can be perfectly well comprehended, even
though we are ignorant of their solution; these
we shall treat by themselves in the next twelve
rules. Finally there are others, whose meaning
is not quite clear, and these we reserve for the
last twelve. This division has been made advisedly,
both in order to avoid mentioning
anything which presupposes an acquaintance
with what follows, and also for the purpose
of unfolding first what we feel to be most
important first to inculcate in cultivating the
mental powers. Among the "questions" whose
meaning is quite plain, we must to begin with
note that we place those only in which we perceive
three things distinctly; to wit, the marks
by which we can identify what we are looking
for when it occurs; what precisely the fact is
from which our answer ought to be deduced;
and how it is to be proved that these (the
ground and its consequence) so depend one on
another that it is impossible for either to
change while the other remains unchanged. In
this way we shall have all the premisses we require,
and the only thing remaining to be shown
will be how to discover the conclusion. This
will not be a matter of deducing some one fact
from a single simple matter (we have already
said that we can do this without the help of
rules), but of disentangling so skilfully some
one fact that is conditioned by a number of
others which all involve one another, that in
recognizing it there shall be no need to call
upon a higher degree of mental power than in
making the simplest inference. "Questions" of
this kind, being highly abstract and occurring
almost exclusively in Arithmetic and Geometry,
seem to the inexperienced of little value.
But I warn them that people ought to busy
and exercise themselves a long time in learning
this art, who desire to master the subsequent
portions of this method, in which all the other
types of "question" are treated.
RULE XIII
Once a "question" is perfectly understood, we
must, free it of every conception superfluous to its
meaning, state it in its simplest terms, and, having
recourse to an enumeration, split it up into the
various sections beyond which analysis cannot go
in minuteness.
THIS is the only respect in which we imitate
the Dialecticians; just as they, in teaching
their doctrine of the forms of syllogism, assume
that the terms or matter of their syllogisms are
already known, so also we on this occasion lay
it down as a prerequisite that the question to
be solved should be perfectly understood. But
we do not, as they, distinguish two extremes
and a middle term. The following is the way in
which we look at the whole matter. Firstly, in
every "question" there must be something of
which we are ignorant; otherwise there is no
use asking the question. Secondly, this very
matter must be disignated in some way or
other; otherwise there would be nothing to determine
us to investigate it rather than anything
else. Thirdly, it can only be so designated
by the aid of something else which is already
known. All three conditions are realised
even in questions that are not fully understood.
Thus if the problem be the nature of the magnet,
we already know what is meant by the
two words "magnet" and "nature," and this
knowledge determines us to seek one sort of
answer rather than another, and so on. But
over and above this, if the question is to be
perfectly stated, we require that it should be
wholly determinate, so that we shall have
nothing more to seek for than what can be inferred
from the data. For example, some one
might set me the question, what is to be inferred
about the nature of the magnet from
that set of experiments precisely which Gilbert
asserts [Presumably the English physicist W, Gilbert
(1540-1603), author of De Magneto (1600)] he has performed, be they trustworthy
or not. So again the question may be,
what my conclusion is as to the nature of
sound, founding my judgment merely on the
precise fact that the three strings A, B, and C
give out an identical sound, when by hypothesis
B, though twice as thick as A, but not
longer, is kept in tension by a weight that is
twice as heavy; while C, though no thicker
than A, but merely twice as long, is nevertheless
kept in tension by a weight four times as
heavy. Other illustrations might be given; but
they all make it quite clear how all imperfectly
expressed "questions" may be reduced toothers
whose meaning is quite clear, as I shall show
at greater length in the proper place. We see
how it is possible to follow this rule in divesting
any difficulty, where the problem is properly
realised, of every superfluous conception,
and in reducing it to a form in which we no
longer deem that we are treating of this or that
special matter, but are dealing only in a general
way with certain magnitudes which have
to be fitted together. Thus, to illustrate, after
we have limited ourselves to the consideration
of this or that set of experiments merely relative
to the magnet, there is no difficulty in dismissing
from view all other aspects of the case.
We add also that the problem ought to be
reduced to its simplest statement in accordance
with Rules V and VI, and resolved into
parts in accordance with Rule VII. Thus if I
employ a number of experiments in investigating
the magnet, I shall run them over successively,
taking each by itself. Again if my
inquiry is about sound, as in the case above, I
shall separately consider the relation between
strings A and B, then that between A and C,
and so on, so that afterwards my enumeration
of results may be sufficient, and may embrace
every case. These three rules are the only ones
which the pure understanding need observe in
dealing with the terms of any proposition before
approaching its ultimate solution, though
that requires us to employ the following eleven
rules. The third part of this Treatise will show
us more clearly how to apply them. Further by
a"question"we understand everything in which
either truth or falsity is found; and we must
enumerate the different types of "question" in
order to determine what we are able to accomplish
in each case.
We have already said that there can be no
falsity in the mere intuition of things, whether
they are simple or united together. So conceived
these are not called "questions," but
they acquire that designation so soon as we
prepare to pass some determinate judgment
about them. Neither do we limit the title to
those questions which are set us by other people.
His own ignorance, or more correctly his
own doubt, presented a subject of inquiry to
Socrates when first he began to study it and to
inquire whether it was true that he doubted
everything, and maintained that such was indeed
the case.
Moreover in our "questions" we seek to derive
either things from words, or causes from
effects, or effects from causes, or the whole or
other parts from parts, or to infer several of
these simultaneously.
We are said to seek to derive things from
words when the difficulty consists merely in
the obscurity of the language employed. To
this class we refer firstly all riddles, like that of
the Sphinx about the animal which to begin
with is four-footed, then two-footed, and finally
three-footed. A similar instance is that of
the fishers who, standing on the bank with
rods and hooks ready for the capture of fish,
said that they no longer possessed those creatures
which they had caught, but on the other
hand those which they had not yet been able
to catch. So in other cases; but besides these,
in the majority of matters on which the learned
dispute, the question is almost always one
of names. We ought not to judge so ill of our
great thinkers as to imagine that they conceive
the objects themselves wrongly, in cases where
they do not employ fit words in explaining
them. Thus when people call place the surface
of the surrounding body, there is no real error
in their conception; they merely employ wrongly
the word place, which by common use signifies
that simple and self-evident nature in virtue
of which a thing is said to be here or there.
This consists wholly in a certain relation of the
thing said to be in the place towards the parts
of the space external to it, and is a feature
which certain writers, seeing that the name
place was reserved for the surface of the surrounding
body, have improperly called the
thing's intrinsic position. So it is in other cases;
indeed these verbal questions are of such frequent
occurrence, that almost all controversy
would be removed from among Philosophers,
if they were always to agree as to the meaning
of words.
We seek to derive causes from effects when
we ask concerning anything, whether it exists
or what it is...
Since, however, when a "question" is propounded
for solution we are frequently unable
at once to discern its type, or to determine
whether the problem is to derive things from
words, or causes from effects, etc., for this reason
it seems to be superfluous to say more here
in detail about these matters. It will occupy
less space and will be more convenient, if at
the same time we go over in order all the steps
which must be followed if we are to solve a
problem of any sort. After that, when any
"question" is set, we must strive to understand
distinctly what the inquiry is about.
For frequently people are in such a hurry in
their investigations, that they bring only a
blank understanding to their solution, without
having settled what the marks are by which
they are to recognize the fact of which they are
in search, if it chance to occur. This is a proceeding
as foolish as that of a boy, who, sent on
an errand by his master, should be so eager to
obey as to run off without having received his
orders or knowing where to go.
However, though in every "question" something
must be unknown, otherwise there is no
need to raise it, we should nevertheless so define
this unknown element by means of specific
conditions that we shall be determined towards
the investigation of one thing rather than another.
These conditions to which, we maintain,
attention must be paid at the very outset.
We shall succeed in this if we so direct our
mental vision as to have a distinct and intuitive
presentation of each by itself, and inquire
diligently bow far the unknown fact for which
we are in search is limited by each. For the
human mind is wont to fall into error in two
ways here; it either assumes more than is really
given in determining the question, or, on the
other hand, leaves something out.
We must take care to assume neither more
nor less than our data furnish us. This applies
chiefly to riddles and other problems where the
object of the skill employed is to try to puzzle
people's wits. But frequently also we must
bear it in mind in other "questions," when it
appears as though we could assume as true for
the purpose of their solution a certain matter
which we have accepted, not because we had a
good reason for doing so, but merely because
we had always believed it. Thus, for example,
in the riddle put by the Sphinx, it is not necessary
to believe that the word "foot"' refers
merely to the real foot of an animal; we must
inquire also whether the term cannot be transferred
to other things, as it may be, as it happens,
to the hands of an infant, or an old man's
staff, because in either case these accessories
are employed as feet are in walking. So too, in
the fishermen's conundrum, we must beware
of letting the thought of fish occupy our minds
to the exclusion of those creatures which the
poor so often carry about with them unwillingly,
and fling away from them when caught.
So again, we must be on our guard when inquiring
into the construction of a vessel, such as we
once saw, in the midst of which stood a column
and upon that a figure of Tantalus in the attitude
of a man who wants to drink. Water when
poured into the vessel remained within without
leaking as long as it was not high enough
to enter the mouth of Tantalus; but as soon as
it touched the unhappy man's lips the whole of
it at once flowed out and escaped. Now at the
first blush it seems as if the whole of the ingenuity
consisted in the construction of this figure
of Tantalus, whereas in reality this is a mere
accompaniment of the fact requiring explanation,
and in no way conditions it. For the whole
difficulty consists solely in the problem of how
the vessel was constructed so as to let out the
whole of the water when that arrived at a certain
height, whereas before none escaped. Finally,
likewise, if we seek to extract from the
recorded observations of the stars an answer
to the question as to what we can assert about
their motions, it is not to be gratuitously assumed
that the earth is immoveable and established
in the midst of the universe, as the Ancients
would have it, because from our earliest
years it appears to be so. We ought to regard
this as dubious, in order afterwards to examine
what certainty there is in this matter to which
we are able to attain. So in other cases.
On the other hand we sin by omission when
there is some condition requisite to the determination
of the question either expressed in it
or in some way to be understood, which we do
not bear in mind. This may happen in an inquiry
into the subject of perpetual motion, not
as we meet with it in nature in the movements
of the stars and the flowing of springs, but as a
motion contrived by human industry. Numbers
of people have believed this to be possible,
their idea being that the earth is in perpetual
motion in a circle round its own axis, while
again the magnet retains all the properties of
the earth. A man might then believe that he
would discover a perpetual motion if he so
contrived it that a magnet should revolve in a
circle, or at least that it communicated its own
motion along with its other properties to a
piece of iron. Now although he were to succeed
in this, it would not be a perpetual motion
artificially contrived; all he did would be to
utilize a natural motion, just as if he were to
station a wheel in the current of a river so as
to secure an unceasing motion on its part.
Thus in his procedure he would have omitted
a condition requisite for the resolution of his
problem.
When we have once adequately grasped the
meaning of a "question," we ought to try and
see exactly wherein the difficulty consists, in
order that, by separating it out from all complicating
circumstances, we may solve it the
more easily. But over and above this we must
attend to the various separate problems involved
in it, in order that if there are any
which are easy to resolve we may omit them;
when these are removed, only that will remain
of which we are still in ignorance. Thus in that
instance of the vessel which was described a
short time ago, it is indeed quite easy to see
how the vessel should be made; a column must
be fixed in its centre, a bird (Translate 'bird' -"a valve must be fitted in it.")
must be painted on it. But all these things will be set aside as
not touching the essential point; thus we are
left with the difficulty by itself, consisting in
the fact that the whole of the water, which had
previously remained in the vessel, after reaching
a certain height, flows out. It is for this
that we have to seek a reason.
Here therefore we maintain that what is
worth while doing is simply this—to explore in
an orderly way all the data furnished by the
proposition, to set aside everything which we
see is clearly immaterial, to retain what is
necessarily bound up with the problem, and to
reserve what is doubtful for a more careful
examination.
RULE XIV
The same rule is to be applied also to the real
extension of bodies. It must be set before the
imagination by means of mere figures, for this is
the best way to make it clear to the understanding.
BUT in proposing to make use of the imagination
as an aid to our thinking, we must note
that whenever one unknown fact is deduced
from another that is already known, that does
not show that we discover any new kind of
entity, but merely that this whole mass of
knowledge is extended in such a way that we
perceive that the matter sought for participates
in one way or another in the nature of
the data given in the proposition. For example
if a man has been blind from his birth it is not
to be expected that we shall be able by any
train of reasoning to make him perceive the
true ideas of the colours which we have derived
from our senses. But if a man has indeed once
perceived the primary colours, though he has
never seen the intermediate or mixed tints, it
is possible for him to construct the images of
those which he has not seen from their likeness
to the others, by a sort of deduction. Similarly
if in the magnet there be any sort of nature the
like of which our mind has never yet known, it
is hopeless to expect that reasoning will ever
make us grasp it; we should have to be furnished
either with some new sense or with a
divine intellect. But we shall believe ourselves
to have attained whatever in this matter can
be achieved by our human faculties, if we discern
with all possible distinctness that mixture
of entities or natures already known which
produces just those effects which we notice in
the magnet.
Indeed all these previously known entities,
viz. extension, figure, motion and the like, the
enumeration of which does not belong to this
place, are recognized by means of an idea
which is one and the same in the various subject
matters. The figure of a silver crown which
we imagine, is just the same as that of one that
is golden. Further this common idea is transferred
from one subject to another, merely by
means of the simple comparison by which we
affirm that the object sought for is in this or
that respect like, or identical with, or equal to
a particular datum. Consequently in every
train of reasoning it is by comparison merely
that we attain to a precise knowledge of the
truth. Here is an example:—all A is B, all B is C,
therefore all A is C. Here we compare with one
another a quaesitum and a datum, viz. A and
C, in respect of the fact that each is B, and so
on. But because, as we have often announced.
the syllogistic forms are of no aid in perceiving
the truth about objects, it will be for the reader's
profit to reject them altogether and to
conceive that all knowledge whatsoever, other
than that which consists in the simple and
naked intuition of single independent objects,
is a matter of the comparison of two things or
more, with each other. In fact practically the
whole of the task set the human reason consists
in preparing for this operation; for when
it is open and simple, we need no aid from art,
but are bound to rely upon the light of nature
alone, in beholding the truth which comparison
gives us. |