SELECTIONS FROM THE PRINCIPLES OF PHILOSOPHY
LETTER
OF THE AUTHOR
Sir,—The
version of my principles which you have been at pains to make, is
so
elegant and finished as to lead me to expect that the work will be
more generally read in French than in Latin, and better understood.
The only apprehension I entertain is lest the title should deter
some
who have not been brought up to letters, or with whom philosophy is
in bad repute, because the kind they were taught has proved
unsatisfactory; and this makes me think that it will be useful to
add
a preface to it for the purpose of showing what the MATTER of the
work is, what END I had in view in writing it, and what UTILITY may
be derived from it. But although it might be my part to write a
preface of this nature, seeing I ought to know those particulars
better than any other person, I cannot nevertheless prevail upon
myself to do anything more than merely to give a summary of the
chief
points that fall, as I think, to be discussed in it: and I leave it
to your discretion to present to the public such part of them as
you
shall judge proper.
I
should have desired, in the first place, to explain in it what
philosophy is, by commencing with the most common matters, as, for
example, that the word PHILOSOPHY signifies the study of wisdom,
and
that by wisdom is to be understood not merely prudence in the
management of affairs, but a perfect knowledge of all that man can
know, as well for the conduct of his life as for the preservation
of
his health and the discovery of all the arts, and that knowledge to
subserve these ends must necessarily be deduced from first causes;
so
that in order to study the acquisition of it (which is properly
called philosophizing), we must commence with the investigation of
those first causes which are called PRINCIPLES. Now these
principles
must possess TWO CONDITIONS: in the first place, they must be so
clear and evident that the human mind, when it attentively
considers
them, cannot doubt of their truth; in the second place, the
knowledge
of other things must be so dependent on them as that though the
principles themselves may indeed be known apart from what depends
on
them, the latter cannot nevertheless be known apart from the
former.
It will accordingly be necessary thereafter to endeavour so to
deduce
from those principles the knowledge of the things that depend on
them, as that there may be nothing in the whole series of
deductions
which is not perfectly manifest. God is in truth the only being who
is absolutely wise, that is, who possesses a perfect knowledge of
all
things; but we may say that men are more or less wise as their
knowledge of the most important truths is greater or less. And I am
confident that there is nothing, in what I have now said, in which
all the learned do not concur.
I
should, in the next place, have proposed to consider the utility of
philosophy, and at the same time have shown that, since it embraces
all that the human mind can know, we ought to believe that it is by
it we are distinguished from savages and barbarians, and that the
civilisation and culture of a nation is regulated by the degree in
which true philosophy nourishes in it, and, accordingly, that to
contain true philosophers is the highest privilege a state can
enjoy.
Besides this, I should have shown that, as regards individuals, it
is
not only useful for each man to have intercourse with those who
apply
themselves to this study, but that it is incomparably better he
should himself direct his attention to it; just as it is doubtless
to
be preferred that a man should make use of his own eyes to direct
his
steps, and enjoy by means of the same the beauties of colour and
light, than that he should blindly follow the guidance of another;
though the latter course is certainly better than to have the eyes
closed with no guide except one's self. But to live without
philosophizing is in truth the same as keeping the eyes closed
without attempting to open them; and the pleasure of seeing all
that
sight discloses is not to be compared with the satisfaction
afforded
by the discoveries of philosophy. And, finally, this study is more
imperatively requisite for the regulation of our manners, and for
conducting us through life, than is the use of our eyes for
directing
our steps. The brutes, which have only their bodies to conserve,
are
continually occupied in seeking sources of nourishment; but men, of
whom the chief part is the mind, ought to make the search after
wisdom their principal care, for wisdom is the true nourishment of
the mind; and I feel assured, moreover, that there are very many
who
would not fail in the search, if they would but hope for success in
it, and knew the degree of their capabilities for it. There is no
mind, how ignoble soever it be, which remains so firmly bound up in
the objects of the senses, as not sometime or other to turn itself
away from them in the aspiration after some higher good, although
not
knowing frequently wherein that good consists. The greatest
favourites of fortune—those who have health, honours, and riches in
abundance— are not more exempt from aspirations of this nature than
others; nay, I am persuaded that these are the persons who sigh the
most deeply after another good greater and more perfect still than
any they already possess. But the supreme good, considered by
natural
reason without the light of faith, is nothing more than the
knowledge
of truth through its first causes, in other words, the wisdom of
which philosophy is the study. And, as all these particulars are
indisputably true, all that is required to gain assent to their
truth
is that they be well stated.
But
as one is restrained from assenting to these doctrines by
experience,
which shows that they who make pretensions to philosophy are often
less wise and reasonable than others who never applied themselves
to
the study, I should have here shortly explained wherein consists
all
the science we now possess, and what are the degrees of wisdom at
which we have arrived. The first degree contains only notions so
clear of themselves that they can be acquired without meditation;
the
second comprehends all that the experience of the senses dictates;
the third, that which the conversation of other men teaches us; to
which may be added as the fourth, the reading, not of all books,
but
especially of such as have been written by persons capable of
conveying proper instruction, for it is a species of conversation
we
hold with their authors. And it seems to me that all the wisdom we
in
ordinary possess is acquired only in these four ways; for I do not
class divine revelation among them, because it does not conduct us
by
degrees, but elevates us at once to an infallible faith.
There
have been, indeed, in all ages great minds who endeavoured to find
a
fifth road to wisdom, incomparably more sure and elevated than the
other four. The path they essayed was the search of first causes
and
true principles, from which might be deduced the reasons of all
that
can be known by man; and it is to them the appellation of
philosophers has been more especially accorded. I am not aware that
there is any one of them up to the present who has succeeded in
this
enterprise. The first and chief whose writings we possess are Plato
and Aristotle, between whom there was no difference, except that
the
former, following in the footsteps of his master, Socrates,
ingenuously confessed that he had never yet been able to find
anything certain, and that he was contented to write what seemed to
him probable, imagining, for this end, certain principles by which
he
endeavoured to account for the other things. Aristotle, on the
other
hand, characterised by less candour, although for twenty years the
disciple of Plato, and with no principles beyond those of his
master,
completely reversed his mode of putting them, and proposed as true
and certain what it is probable he himself never esteemed as such.
But these two men had acquired much judgment and wisdom by the four
preceding means, qualities which raised their authority very high,
so
much so that those who succeeded them were willing rather to
acquiesce in their opinions, than to seek better for themselves.
The
chief question among their disciples, however, was as to whether we
ought to doubt of all things or hold some as certain,—a dispute
which led them on both sides into extravagant errors; for a part of
those who were for doubt, extended it even to the actions of life,
to
the neglect of the most ordinary rules required for its conduct;
those, on the other hand, who maintained the doctrine of certainty,
supposing that it must depend upon the senses, trusted entirely to
them. To such an extent was this carried by Epicurus, that it is
said
he ventured to affirm, contrary to all the reasonings of the
astronomers, that the sun is no larger than it appears.
It
is a fault we may remark in most disputes, that, as truth is the
mean
between the two opinions that are upheld, each disputant departs
from
it in proportion to the degree in which he possesses the spirit of
contradiction. But the error of those who leant too much to the
side
of doubt, was not followed for any length of time, and that of the
opposite party has been to some extent corrected by the doctrine
that
the senses are deceitful in many instances. Nevertheless, I do not
know that this error was wholly removed by showing that certitude
is
not in the senses, but in the understanding alone when it has clear
perceptions; and that while we only possess the knowledge which is
acquired in the first four grades of wisdom, we ought not to doubt
of
the things that appear to be true in what regards the conduct of
life, nor esteem them as so certain that we cannot change our
opinions regarding them, even though constrained by the evidence of
reason.
From
ignorance of this truth, or, if there was any one to whom it was
known, from neglect of it, the majority of those who in these later
ages aspired to be philosophers, blindly followed Aristotle, so
that
they frequently corrupted the sense of his writings, and attributed
to him various opinions which he would not recognise as his own
were
he now to return to the world; and those who did not follow him,
among whom are to be found many of the greatest minds, did yet not
escape being imbued with his opinions in their youth, as these form
the staple of instruction in the schools; and thus their minds were
so preoccupied that they could not rise to the knowledge of true
principles. And though I hold all the philosophers in esteem, and
am
unwilling to incur odium by my censure, I can adduce a proof of my
assertion, which I do not think any of them will gainsay, which is,
that they all laid down as a principle what they did not perfectly
know. For example, I know none of them who did not suppose that
there
was gravity in terrestrial bodies; but although experience shows us
very clearly that bodies we call heavy descend towards the center
of
the earth, we do not, therefore, know the nature of gravity, that
is,
the cause or principle in virtue of which bodies descend, and we
must
derive our knowledge of it from some other source. The same may be
said of a vacuum and atoms, of heat and cold, of dryness and
humidity, and of salt, sulphur, and mercury, and the other things
of
this sort which some have adopted as their principles. But no
conclusion deduced from a principle which is not clear can be
evident, even although the deduction be formally valid; and hence
it
follows that no reasonings based on such principles could lead them
to the certain knowledge of any one thing, nor consequently advance
them one step in the search after wisdom. And if they did discover
any truth, this was due to one or other of the four means above
mentioned. Notwithstanding this, I am in no degree desirous to
lessen
the honour which each of them can justly claim; I am only
constrained
to say, for the consolation of those who have not given their
attention to study, that just as in travelling, when we turn our
back
upon the place to which we were going, we recede the farther from
it
in proportion as we proceed in the new direction for a greater
length
of time and with greater speed, so that, though we may be
afterwards
brought back to the right way, we cannot nevertheless arrive at the
destined place as soon as if we had not moved backwards at all; so
in
philosophy, when we make use of false principles, we depart the
farther from the knowledge of truth and wisdom exactly in
proportion
to the care with which we cultivate them, and apply ourselves to
the
deduction of diverse consequences from them, thinking that we are
philosophizing well, while we are only departing the farther from
the
truth; from which it must be inferred that they who have learned
the
least of all that has been hitherto distinguished by the name of
philosophy are the most fitted for the apprehension of
truth.
After
making those matters clear, I should, in the next place, have
desired
to set forth the grounds for holding that the true principles by
which we may reach that highest degree of wisdom wherein consists
the
sovereign good of human life, are those I have proposed in this
work;
and two considerations alone are sufficient to establish this—the
first of which is, that these principles are very clear, and the
second, that we can deduce all other truths from them; for it is
only
these two conditions that are required in true principles. But I
easily prove that they are very clear; firstly, by a reference to
the
manner in which I found them, namely, by rejecting all propositions
that were in the least doubtful, for it is certain that such as
could
not be rejected by this test when they were attentively considered,
are the most evident and clear which the human mind can know. Thus
by
considering that he who strives to doubt of all is unable
nevertheless to doubt that he is while he doubts, and that what
reasons thus, in not being able to doubt of itself and doubting
nevertheless of everything else, is not that which we call our
body,
but what we name our mind or thought, I have taken the existence of
this thought for the first principle, from which I very clearly
deduced the following truths, namely, that there is a God who is
the
author of all that is in the world, and who, being the source of
all
truth, cannot have created our understanding of such a nature as to
be deceived in the judgments it forms of the things of which it
possesses a very clear and distinct perception. Those are all the
principles of which I avail myself touching immaterial or
metaphysical objects, from which I most clearly deduce these other
principles of physical or corporeal things, namely, that there are
bodies extended in length, breadth, and depth, which are of diverse
figures and are moved in a variety of ways. Such are in sum the
principles from which I deduce all other truths. The second
circumstance that proves the clearness of these principles is, that
they have been known in all ages, and even received as true and
indubitable by all men, with the exception only of the existence of
God, which has been doubted by some, because they attributed too
much
to the perceptions of the senses, and God can neither be seen nor
touched.
But,
though all the truths which I class among my principles were known
at
all times, and by all men, nevertheless, there has been no one up
to
the present, who, so far as I know, has adopted them as principles
of
philosophy: in other words, as such that we can deduce from them
the
knowledge of whatever else is in the world. It accordingly now
remains for me to prove that they are such; and it appears to me
that
I cannot better establish this than by the test of experience: in
other words, by inviting readers to peruse the following work. For,
though I have not treated in it of all matters- -that being
impossible—I think I have so explained all of which I had occasion
to treat, that they who read it attentively will have ground for
the
persuasion that it is unnecessary to seek for any other principles
than those I have given, in order to arrive at the most exalted
knowledge of which the mind of man is capable; especially if, after
the perusal of my writings, they take the trouble to consider how
many diverse questions are therein discussed and explained, and,
referring to the writings of others, they see how little
probability
there is in the reasons that are adduced in explanation of the same
questions by principles different from mine. And that they may the
more easily undertake this, I might have said that those imbued
with
my doctrines have much less difficulty in comprehending the
writings
of others, and estimating their true value, than those who have not
been so imbued; and this is precisely the opposite of what I before
said of such as commenced with the ancient philosophy, namely, that
the more they have studied it the less fit are they for rightly
apprehending the truth.
I
should also have added a word of advice regarding the manner of
reading this work, which is, that I should wish the reader at first
to go over the whole of it, as he would a romance, without greatly
straining his attention, or tarrying at the difficulties he may
perhaps meet with in it, with the view simply of knowing in general
the matters of which I treat; and that afterwards, if they seem to
him to merit a more careful examination, and he feel a desire to
know
their causes, he may read it a second time, in order to observe the
connection of my reasonings; but that he must not then give it up
in
despair, although he may not everywhere sufficiently discover the
connection of the proof, or understand all the reasonings—it being
only necessary to mark with a pen the places where the difficulties
occur, and continue to read without interruption to the end; then,
if
he does not grudge to take up the book a third time, I am confident
he will find in a fresh perusal the solution of most of the
difficulties he will have marked before; and that, if any still
remain, their solution will in the end be found in another
reading.
I
have observed, on examining the natural constitutions of different
minds, that there are hardly any so dull or slow of understanding
as
to be incapable of apprehending good opinions, or even of acquiring
all the highest sciences, if they be but conducted along the right
road. And this can also be proved by reason; for, as the principles
are clear, and as nothing ought to be deduced from them, unless
most
manifest inferences, no one is so devoid of intelligence as to be
unable to comprehend the conclusions that flow from them. But,
besides the entanglement of prejudices, from which no one is
entirely
exempt, although it is they who have been the most ardent students
of
the false sciences that receive the greatest detriment from them,
it
happens very generally that people of ordinary capacity neglect to
study from a conviction that they want ability, and that others,
who
are more ardent, press on too rapidly: whence it comes to pass that
they frequently admit principles far from evident, and draw
doubtful
inferences from them. For this reason, I should wish to assure
those
who are too distrustful of their own ability that there is nothing
in
my writings which they may not entirely understand, if they only
take
the trouble to examine them; and I should wish, at the same time,
to
warn those of an opposite tendency that even the most superior
minds
will have need of much time and attention to remark all I designed
to
embrace therein.
After
this, that I might lead men to understand the real design I had in
publishing them, I should have wished here to explain the order
which
it seems to me one ought to follow with the view of instructing
himself. In the first place, a man who has merely the vulgar and
imperfect knowledge which can be acquired by the four means above
explained, ought, before all else, to endeavour to form for himself
a
code of morals, sufficient to regulate the actions of his life, as
well for the reason that this does not admit of delay as because it
ought to be our first care to live well. In the next place, he
ought
to study Logic, not that of the schools, for it is only, properly
speaking, a dialectic which teaches the mode of expounding to
others
what we already know, or even of speaking much, without judgment,
of
what we do not know, by which means it corrupts rather than
increases
good sense—but the logic which teaches the right conduct of the
reason with the view of discovering the truths of which we are
ignorant; and, because it greatly depends on usage, it is desirable
he should exercise himself for a length of time in practising its
rules on easy and simple questions, as those of the mathematics.
Then, when he has acquired some skill in discovering the truth in
these questions, he should commence to apply himself in earnest to
true philosophy, of which the first part is Metaphysics, containing
the principles of knowledge, among which is the explication of the
principal attributes of God, of the immateriality of the soul, and
of
all the clear and simple notions that are in us; the second is
Physics, in which, after finding the true principles of material
things, we examine, in general, how the whole universe has been
framed; in the next place, we consider, in particular, the nature
of
the earth, and of all the bodies that are most generally found upon
it, as air, water, fire, the loadstone and other minerals. In the
next place it is necessary also to examine singly the nature of
plants, of animals, and above all of man, in order that we may
thereafter be able to discover the other sciences that are useful
to
us. Thus, all Philosophy is like a tree, of which Metaphysics is
the
root, Physics the trunk, and all the other sciences the branches
that
grow out of this trunk, which are reduced to three principal,
namely,
Medicine, Mechanics, and Ethics. By the science of Morals, I
understand the highest and most perfect which, presupposing an
entire
knowledge of the other sciences, is the last degree of
wisdom.
TO
THE MOST SERENE PRINCESS,
ELIZABETH,
ELDEST DAUGHTER OF FREDERICK, KING OF BOHEMIA, COUNT PALATINE, AND
ELECTOR OF THE SACRED ROMAN EMPIRE.
MADAM,—The
greatest advantage I have derived from the writings which I have
already published, has arisen from my having, through means of
them,
become known to your Highness, and thus been privileged to hold
occasional converse with one in whom so many rare and estimable
qualities are united, as to lead me to believe I should do service
to
the public by proposing them as an example to posterity. It would
ill
become me to flatter, or to give expression to anything of which I
had no certain knowledge, especially in the first pages of a work
in
which I aim at laying down the principles of truth. And the
generous
modesty that is conspicuous in all your actions, assures me that
the
frank and simple judgment of a man who only writes what he believes
will be more agreeable to you than the ornate laudations of those
who
have studied the art of compliment. For this reason, I will give
insertion to nothing in this letter for which I have not the
certainty both of experience and reason; and in the exordium, as in
the rest of the work, I will write only as becomes a philosopher.
There is a vast difference between real and apparent virtues; and
there is also a great discrepancy between those real virtues that
proceed from an accurate knowledge of the truth, and such as are
accompanied with ignorance or error. The virtues I call apparent
are
only, properly speaking, vices, which, as they are less frequent
than
the vices that are opposed to them, and are farther removed from
them
than the intermediate virtues, are usually held in higher esteem
than
those virtues. Thus, because those who fear dangers too much are
more
numerous than they who fear them too little, temerity is frequently
opposed to the vice of timidity, and taken for a virtue, and is
commonly more highly esteemed than true fortitude. Thus, also, the
prodigal are in ordinary more praised than the liberal; and none
more
easily acquire a great reputation for piety than the superstitious
and hypocritical. With regard to true virtues, these do not all
proceed from true knowledge, for there are some that likewise
spring
from defect or error; thus, simplicity is frequently the source of
goodness, fear of devotion, and despair of courage. The virtues
that
are thus accompanied with some imperfections differ from each
other,
and have received diverse appellations. But those pure and perfect
virtues that arise from the knowledge of good alone are all of the
same nature, and may be comprised under the single term wisdom.
For,
whoever owns the firm and constant resolution of always using his
reason as well as lies in his power, and in all his actions of
doing
what he judges to be best, is truly wise, as far as his nature
permits; and by this alone he is just, courageous, temperate, and
possesses all the other virtues, but so well balanced as that none
of
them appears more prominent than another: and for this reason,
although they are much more perfect than the virtues that blaze
forth
through the mixture of some defect, yet, because the crowd thus
observes them less, they are not usually extolled so highly.
Besides,
of the two things that are requisite for the wisdom thus described,
namely, the perception of the understanding and the disposition of
the will, it is only that which lies in the will which all men can
possess equally, inasmuch as the understanding of some is inferior
to
that of others. But although those who have only an inferior
understanding may be as perfectly wise as their nature permits, and
may render themselves highly acceptable to God by their virtue,
provided they preserve always a firm and constant resolution to do
all that they shall judge to be right, and to omit nothing that may
lead them to the knowledge of the duties of which they are
ignorant;
nevertheless, those who preserve a constant resolution of
performing
the right, and are especially careful in instructing themselves,
and
who possess also a highly perspicacious intellect, arrive doubtless
at a higher degree of wisdom than others; and I see that these
three
particulars are found in great perfection in your Highness. For, in
the first place, your desire of self-instruction is manifest, from
the circumstance that neither the amusements of the court, nor the
accustomed mode of educating ladies, which ordinarily condemns them
to ignorance, have been sufficient to prevent you from studying
with
much care all that is best in the arts and sciences; and the
incomparable perspicacity of your intellect is evinced by this,
that
you penetrated the secrets of the sciences and acquired an accurate
knowledge of them in a very short period. But of the vigour of your
intellect I have a still stronger proof, and one peculiar to
myself,
in that I have never yet met any one who understood so generally
and
so well as yourself all that is contained in my writings. For there
are several, even among men of the highest intellect and learning,
who find them very obscure. And I remark, in almost all those who
are
versant in Metaphysics, that they are wholly disinclined from
Geometry; and, on the other hand, that the cultivators of Geometry
have no ability for the investigations of the First Philosophy:
insomuch that I can say with truth I know but one mind, and that is
your own, to which both studies are alike congenial, and which I
therefore, with propriety, designate incomparable. But what most of
all enhances my admiration is, that so accurate and varied an
acquaintance with the whole circle of the sciences is not found in
some aged doctor who has employed many years in contemplation, but
in
a Princess still young, and whose countenance and years would more
fitly represent one of the Graces than a Muse or the sage Minerva.
In
conclusion, I not only remark in your Highness all that is
requisite
on the part of the mind to perfect and sublime wisdom, but also all
that can be required on the part of the will or the manners, in
which
benignity and gentleness are so conjoined with majesty that, though
fortune has attacked you with continued injustice, it has failed
either to irritate or crush you. And this constrains me to such
veneration that I not only think this work due to you, since it
treats of philosophy which is the study of wisdom, but likewise
feel
not more zeal for my reputation as a philosopher than pleasure in
subscribing myself,—
Of
your most Serene Highness, The most devoted servant,
DESCARTES.
