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Rene Descartes
Discourse on the Method for Reasoning
Well and for Seeking Truth in the Sciences
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Translated by
Ian Johnston
Vancouver Island University
Nanaimo, BC
Canada
[Revised May 2010]
[For details about use of this text, please see Copyright]
HISTORICAL NOTE
René Descartes (1596-1650) published Discourse on
Method in 1637 as part of a work containing sections on optics, geometry,
and meteorology. The fourth section, the Discourse, outlined the
basis for a new method of investigating knowledge. He later (in 1641) published
a more detailed exploration of the philosophical basis for this new approach to
knowledge in Meditations on First Philosophy.
TABLE OF CONTENTS
[Preface]—Part
One—Part Two—Part Three—Part Four—Part Five
Part Six—Notes
RENÉ DESCARTES
DISCOURSE ON METHOD
[PREFACE]1
If this discourse seems too long to be read in a single sitting, it
can be divided up into six parts. In the first will be found various
considerations concerning the sciences; in the second, the principal rules of
the method which the author has discovered; in the third, some rules of
morality which he has derived by this method; in the fourth, the reasons which
enable him to establish the existence of God and of the human soul, which are
the foundations of his metaphysics; in the fifth part, the order of questions
in physics which he has looked into, and particularly the explanation for the
movements of the heart and for some other difficulties which are part of
medicine, including the difference which exists between our souls and those of
animals; in the last part, some matters he believes necessary for further
advances in research into nature, beyond where he has been, along with some reasons
which have induced him to write.
The most widely shared thing in the world is good sense, for everyone
thinks he is so well provided with it that even those who are the most
difficult to satisfy in everything else do not usually desire to have more good
sense than they have. In this matter it is not likely that everyone is
mistaken. But this is rather a testimony to the fact that the power of judging
well and distinguishing what is true from what is false, which is really what
we call good sense or reason, is naturally equal in all men, and thus the
diversity of our opinions does not arise because some people are more
reasonable than others, but only because we conduct our thoughts by different
routes and do not consider the same things. For it is not enough to have a good
mind. The main thing is to apply it well. The greatest minds are capable of the
greatest vices as well as the greatest virtues, and those who proceed only very
slowly, if they always stay on the right road, are capable of advancing a great
deal further than those who rush along and wander away from it.
As for myself, I have never presumed that my mind was anything
more perfect than the ordinary mind. I have often even wished that I could have
thoughts as quick, an imagination as clear and distinct, or a memory as ample
or as actively involved as some other people. And I know of no qualities other
than these which serve to perfect the mind. As far as reason, or sense, is
concerned, given that it is the only thing which makes us human and distinguishes
us from the animals, I like to believe that it is entirely complete in each
person, following in this the common opinion of philosophers, who say that
differences of more and less should occur only between accidental
characteristics and not at all between the forms or
natures of individuals of the same species.
But I will not hesitate to state that I think I have been very fortunate
to have found myself since my early years on certain roads which have led me to
considerations and maxims out of which I have created a method by which, it
seems to me, I have a way of gradually increasing my knowledge, raising it little
by little to the highest point which the mediocrity of my mind and the short
length of my life can allow it to attain. For I have already harvested such
fruit from this method that, even though, in judging myself, I always try to
lean towards the side of distrust rather than to that of presumption and although,
when I look with a philosopher's eye on the various actions and enterprises of
all men, there are hardly any which do not seem to me vain and useless, I cannot
help deriving extreme satisfaction from the progress which I think I have
already made in my research into the truth and conceiving such hopes for the future
that, if among the occupations of men, simply as men, there is one which is
surely good and important, I venture to think it is the one I have chosen.
However, it could be the case that I am wrong and that perhaps
what I have taken for gold and diamonds is only a little copper and glass. I
know how much we are subject to making mistakes in what touches ourselves and
also how much we should beware of the judgments of our friends when they are in
our favour. But I will be only too happy to make
known in this discourse what roads I have followed and to reveal my life in it,
as if in a picture, so that each person can judge it. Learning from current
reports the opinions people have of this discourse may be a new way of educating myself, something I will add to those which I habitually
use.
Thus, my design here is not to teach the method which everyone
should follow in order to reason well, but merely to reveal the way in which I
have tried to conduct my own reasoning. Those who take it upon themselves to
give precepts must consider themselves more skilful than those to whom they
give them, and if they are missing the slightest thing, then they are culpable.
But since I intend this text only as a history, or, if you prefer, a fable, in
which, among some examples which you can imitate, you will, in addition,
perhaps find several others which you will have reason not to follow, I hope
that it will be useful to some people, without harming anyone, and that
everyone will find my frankness agreeable.
I was nourished on literature from the time of my childhood.
Because people persuaded me that through literature one could acquire a clear
and assured understanding of everything useful in life, I had an intense desire
to take it up. But as soon as I had completed that entire course of study at
the end of which one was usually accepted into the rank of scholars, I changed
my opinion completely. For I found myself burdened by so many doubts and errors
that it seemed to me I had gained nothing by trying to instruct myself, other
than the fact that I had increasingly discovered my own ignorance. Yet I had
been in one of the most famous schools in Europe, a place where I thought there
must be erudite men, if there were such people anywhere on earth. I had learned
everything which the others learned there, but still, not being happy with the
sciences which we were being taught, I had gone through all the books which I
could lay my hands on dealing with those sciences which are
considered the most curious and rare.2 In addition, I
knew how other people were judging me, and I saw that they did not consider me
inferior to my fellow students, although among them there were already some destined
to fill the places of our teachers. And finally our age
seemed to me as flourishing and as fertile in good minds as any preceding age. Hence,
I took the liberty of judging all the others by myself and of thinking that
there was no doctrine in the world of the kind I had previously been led to
hope for.
However, I did not cease valuing the exercises which kept people
busy in the schools. I knew that the languages one learns there are necessary
for an understanding of ancient books, that the gracefulness of fables awakens
the intellect, that the memorable actions of history raise the mind, and if one
reads with discretion, help to form one's judgment, that reading all the good
books is like a conversation with the most honourable
people of past centuries, who were their authors, even a carefully prepared
dialogue in which they reveal to us only the best of their thoughts, that
eloquence has incomparable power and beauty, that poetry has a most ravishing
delicacy and softness, that mathematics has very skillful inventions which can
go a long way toward satisfying the curious as well as facilitating all the
arts and lessening the work of men, that the writings which deal with morals
contain several lessons and a number of exhortations to virtue which are extremely
useful, that theology teaches one how to reach heaven, that philosophy provides
a way of speaking plausibly on all matters and making oneself admired by those
who are less scholarly, that jurisprudence, medicine, and the other sciences
bring honour and riches to those who cultivate them,
and finally that it is good to have examined all of them, even the most
superstitious and false, in order to know their legitimate value and to guard
against being wrong. But I believed I had already given enough time to
languages and even to reading ancient books as well, and to their histories and
stories. For talking with those from other ages is almost the same as
travelling. It is good to know something about the customs of various people,
so that we can judge our own more sensibly and do not think everything different
from our own ways ridiculous and irrational, as those who have seen nothing are
accustomed to do. But when one spends too much time travelling, one finally
becomes a stranger in one's own country, and when one is too curious about
things which went on in past ages, one
usually lives in considerable ignorance about what goes on in this one. In addition,
fables make us imagine several totally impossible events as possible, and even
the most faithful histories, if they neither change nor increase the importance
of things to make them more worth reading, at the very least almost always omit
the most menial and less admirable circumstances, with the result that what is
left in does not depict the truth. Hence, those who regulate their habits by
the examples which they derive from these histories are prone to fall into the
extravagances of the knights of our romances and to dream up projects which
exceed their powers.
I placed a great value on eloquence, and I was in love with
poetry, but I thought that both of them were gifts given to the mind rather
than fruits of study. Those who have the most powerful reasoning and who direct
their thoughts best in order to make them clear and intelligible can always
convince us best of what they are proposing, even if they speak only the
language of Lower Brittany and have never learned rhetoric. And those who
possess the most pleasant creative talents and who know how to express them
with the most adornment and smoothness cannot help being the best poets, even
though the art of poetry is unknown to them.
I found mathematics especially delightful because of the certainty
and clarity of its reasoning. But I did not yet notice its true use. Thinking
that it was practical only in the mechanical arts, I was astonished that on its
foundations, so strong and solid, nothing more imposing had been built up. By
contrast, I compared the writings of the ancient pagans which deal with
morality to really superb and magnificent palaces built on nothing but sand and
mud. They raise the virtues to a very great height and make them appear
valuable, above everything in the world, but they do not teach us to know them
well enough, and often what they call by such a beautiful name
is only apathy or pride or despair or parricide.3
I revered our theology and aspired as much as anyone to reach
heaven, but having learned, as something very certain, that the road there is
no less open to the most ignorant as to the most learned and that the revealed
truths which lead there are beyond our intelligence, I did not dare to submit
them to the frailty of my reasoning, and I thought that undertaking to examine
them successfully would require me to have some extraordinary heavenly
assistance and to be more than a man.
I will say nothing of philosophy other than this: once I saw that
it had been cultivated for several centuries by the most excellent minds which
had ever lived, and that, nonetheless, there was still nothing in it which was
not disputed and which was thus not still in doubt, I did not have sufficient
presumption to hope to fare better there than the others. Considering how many
different opinions, maintained by learned people, philosophy could have about
the same matter, without there ever being more than one which could be true, I
reckoned as virtually false all those which were merely probable.
Then, as for the other sciences, since they borrow their principles
from philosophy, I judged that nothing solid could have been built on such
insubstantial foundations, and neither the honour nor
the profit which they promise were sufficient to convince me to learn them,
for, thank God, I did not feel myself in a condition which obliged me to make a
profession of science in order improve my fortune, and, although I did not, in
some cynical way, undertake to proclaim my disdain for glory, nonetheless I
placed very little value on the fame I could hope to acquire only through false
titles. And finally, as for bad doctrines, I thought I already understood
sufficiently what they were worth in order not be taken in either by the promises
of an alchemist, by the predictions of an astrologer, by the impostures of a
magician, or by the artifice or the bragging of any of those who made a
profession of knowing more than they know.
That is why, as soon as my age permitted me to leave the supervision
of my professors, I completely stopped the study of letters, and, resolving not
to look any more in any other science except one which could be found inside
myself or in the great book of the world, I spent the rest of my youth
travelling, looking into courts and armies, associating with people of various humours and conditions, collecting various experiences,
testing myself in the encounters which fortune offered me, and everywhere
reflecting on the things I came across in such a way that I could draw some
profit from them. For it seemed to me that I could arrive at considerably more
truth in the reasoning that each man makes concerning the matters which are
important to him and in which events could punish him soon afterwards if he
judged badly, than in the reasoning made by a man of letters in his study
concerning speculations which produce no effect and which are of no consequence
to him, except perhaps that from them he can augment his vanity—and all the
more so, the further his speculations are from common sense, because he would
have had to use that much more wit and artifice in the attempt to make them
probable. And I always had an extreme desire to learn to distinguish the true
from the false, in order to see clearly in my actions and to proceed with confidence
in this life.
It is true that while I did nothing but examine the customs of
other men, I found hardly anything there to reassure me, and I noticed as much
diversity among men as I had earlier among the opinions of philosophers. Consequently,
the greatest profit which I derived from this was that, by seeing several
things which, although they seem really extravagant and ridiculous to us, were
commonly accepted and approved by other great people, I learned not to believe
too firmly in anything which I had been persuaded to believe merely by example
and by custom. Thus, I gradually freed myself of plenty of errors which can
obfuscate our natural light and make us less capable of listening to reason.
But after I had spent a few years studying in this way in the book of the
world, attempting to acquire some experience, one day I resolved to study myself
as well and to use all the powers of my mind to select paths which I should
follow, a task which brought me considerably more success, it seems to me, than
if I had never gone away from my own country and my books.
I was then in Germany, summoned by the wars which
have not yet concluded there.4 As I was returning to the army from
the coronation of the emperor, the onset of winter stopped me in a place where,
not finding any conversation to divert me and in addition, by good fortune, not
having any cares or passions to trouble me, I spent the entire day closed up
alone in a room heated by a stove, where I had complete leisure to talk to
myself about my thoughts. Among these, one of the first was that I noticed
myself thinking about how often there is not so much perfection in works
created from several pieces and made by the hands of various masters as there
is in those which one person has worked on alone. Thus, we see that the
buildings which a single architect has undertaken and completed are usually
more beautiful and better ordered than those which several people have tried to
refurbish by making use of old walls built for other purposes. That is why
those ancient cities which were only small villages at the start and became
large towns over time are ordinarily so badly laid out, compared to the regular
places which an engineer has designed freely on level ground. Even though,
considering the buildings in each of them separately, we often find as much
beauty in the former town as in the latter, or more, nonetheless, looking at
them as they are arranged—here a large one, there a small one—and the way they
make the streets crooked and unequal, we would say that chance rather than the
will of some men using their reason designed them this way. And if one considers
that nonetheless there have always been certain officials charged with seeing
that private buildings serve as a public ornament, one will readily see that it
is difficult to achieve really fine things by working only with other people's
pieces. Thus, I imagined to myself that people who were semi-savages in earlier
times and who became civilized only little by little and created their laws
only as they were compelled to by the extent to which crimes and quarrels
bothered them would not be so well regulated as those who, from the moment they
first assembled, followed the constitution of some prudent legislator. It is
indeed certain that the state of the true religion, whose laws God alone
created, must be incomparably better ordered than all the others. And, to speak
of human affairs, I believe that if Sparta was in earlier times very
prosperous, that was not on account of the goodness of each of its laws in
particular, seeing that several were very strange and even contrary to good
morals, but on account of the fact that they were devised by only a single man
and thus they contributed towards the same end. Similarly I thought that the
sciences contained in books, at least those whose reasons are only probable and
without any proofs, since they were put together and crudely fashioned little
by little out of the opinions of several different people, therefore did not approach
the truth as much as the simple reasoning which a man of good sense can make
quite naturally concerning matters of his own experience. In the same way I
thought that because we were all children before we were men and because it was
necessary for us to be governed for a long time by our appetites and our
supervisors, who were often at odds with each other, with neither of them
perhaps advising us always for the best, it is almost impossible that our
judgments are as pure and solid as they would have been if we had had the total
use of our reason from the moment of our birth and had never been led by
anything but our reason.
It is true that we see little point in demolishing all the houses
of a city for the sole purpose of rebuilding them in another way and thus
making the streets more beautiful. But we do see several people demolish their
houses in order to rebuild them, and, indeed, sometimes they are compelled to
do so, when the houses are in danger of collapsing on their own and when their
foundations are not steady. This example persuaded me that there would probably
be little point for a particular man to draw up a design for reforming a state,
changing all of it from the foundations, overturning it in order to put it up
again, or even for reforming the body of sciences or the order established in
the schools for teaching the sciences. But so far as all the opinions which I
had received up to that point and which I believed credible were concerned, I
convinced myself that the best possible thing for me to do was to undertake to
remove them once and for all, so that afterwards I could replace them either by
other better ones or perhaps by the same ones, once I had adjusted them to a
reasonable standard. And I firmly believed that by this means I would be
successful in conducting my life much better than if I built only on the old
foundations and relied only on principles which I had been persuaded to accept
in my youth, without ever having examined whether they were true. For, although
I recognized various problems with this approach, these were not without remedy
and could not compare to those which occur in the reform of the least matters
concerning the public. It is too difficult to re-erect those large bodies if
they are thrown down or even to keep them once they are weakened, and their collapses
cannot be anything but very drastic. Then, as far as the imperfections of large
public bodies are concerned, if they have any (and the variety among such
bodies alone is sufficient to assure us that there are several imperfections),
habit has no doubt considerably softened these and has even managed to avoid
some problems or corrected a number of them insensibly, which people's caution
could not have managed so well, and finally the imperfections are almost always
easier to bear than changing them would be, in the same way that the major
roads which wind among the mountains gradually become so smooth and convenient
from being used, that it is much better to follow them than to set out to go
more directly by climbing up over the rocks and going down right to the bottom
of the precipices.
That is why I cannot approve at all of those muddled and worried
temperaments who, without being summoned by their birth or fortune to the management
of public business, never stop proposing some idea for a new reform in it. If I
thought that there was the slightest thing in this text which would enable
someone to suspect me of this foolishness, I would be very reluctant to allow
it to be published. My intention has never been to do more than try to reform
my own thoughts and to build on a foundation which is entirely my own. And if
my work has pleased me sufficiently to make me show you the model of it here, that
is not because I wish to advise anyone to imitate it. Those to whom God has given
more of his grace will perhaps have loftier intentions, but I fear that this
work may already be too bold for several people. The single resolution to strip
away all the opinions which one has previously absorbed into one's beliefs is
not an example which everyone should follow. Most of the world is made up of
two sorts of minds for whom such a resolution is not suitable. First, there are
those who, believing themselves more clever than they are, cannot stop making
hasty judgments, without having enough patience to conduct their thoughts in an
orderly way, with the result that, once they have taken the liberty of doubting
the principles they have received and of leaving the common road, they will
never be able to hold to the track which they need to take in order to proceed
more directly and will remain lost all their lives. Then, there are the ones
who, having sufficient reason or modesty to judge that they are less capable of
differentiating truth and falsehood than several others from whom they can be
instructed, must content themselves with following the opinions of these others
rather than searching for better opinions on their own.
As for me, I would have undoubtedly been among the number of this
latter group if I had only had a single master or if I had known nothing at all
about the differences which have always existed among the opinions of the most
highly educated men. But I learned from my college days on that one cannot
imagine anything so strange and so incredible that it has not been said by some
philosopher and, later, in my travelling, I found out that all those who have
views very different from our own are not therefore barbarians or savages, but
that several use as much reason as we do, or more. I also considered how much
the same man, with the same mind, raised from his infancy on among the French
or the Germans, would become different from what he would have been if he had always
lived among the Chinese or the cannibals, and how, even in our style of dress
the same thing which pleased us ten years ago and which will perhaps please us
again ten years from today, now seems to us extravagant and ridiculous. This
being the case, we are clearly persuaded more by custom and example than by any
certain knowledge. Nonetheless, a plurality of voices is not a proof worth
anything for truths which are a little difficult to discover, because it is far
more probable that one man by himself would have found them than an entire
people. Since I could not select anyone whose opinions it seemed to me one
should prefer to those of other people, I found myself, so to speak, compelled
to guide myself on my own.
But like a man who proceeds alone and in the shadows, I resolved
to go so slowly and to use so much circumspection in all matters, that if I only advanced a very short distance,
at least I would take good care not to fall. I did not even wish to begin by
rejecting completely any of the opinions which could have slipped into my
beliefs previously without being introduced by reason, before I had taken up
enough time drawing up a plan for the work I was undertaking and seeking out
the true method for arriving at an understanding of everything my mind was
capable of knowing.
When I was younger, among the branches of philosophy, I had
studied a little logic and, among the subjects of mathematics, geometrical
analysis and algebra, three arts or sciences which looked as if they ought to
contribute something to my project. But in looking at them, I took care,
because, so far as logic is concerned, its syllogisms and most of its other
instructions serve to explain to others what one already knows or even, as in
the art of Lully, to speak without judgment of things about
which one is ignorant, rather than to learn what they are.5 Although
philosophy does, in fact, contain many really true and excellent precepts,
mixed in with them there are always so many injurious or superfluous ones that
it is almost as difficult to separate them as to draw a Diana or a Minerva out
of a block of marble which has not yet been carved. Then, so far as the
analysis of the ancients and the algebra of the moderns are concerned, other
than the fact that they deal only with really abstract matters, which have no
apparent use, the former is always so concentrated on considering numbers that
it cannot exercise the understanding without considerably tiring the
imagination, and in the latter is so subject to certain rules and symbols that
it has been turned into a confused and obscure art which clutters up the mind rather
than a science which cultivates it. Those were the reasons why I thought I had
to look for some other method which included the advantages of these three
subjects but was free of their defects. And since a multitude of laws often
provides excuses for vices, so that a state is much better ruled when it has
only a very few laws which are very strictly observed, I thought that, instead
of that large number of rules which make up logic, I would have enough with the
four following rules, provided that I maintained a strong and constant
resolution that I would never fail to observe them, not even once.
The first rule was that I would not accept anything as true which
I did not clearly know to be true. That is to say, I would carefully avoid
being over hasty or prejudiced, and I would understand nothing by my judgments
beyond what presented itself so clearly and distinctly to my mind
that I had no occasion to doubt it.6
The second was to divide each difficulty which I examined into as
many parts as possible and as might be necessary to resolve it better.
The third was to conduct my thoughts in an orderly way, beginning
with the simplest objects, the ones easiest to know, so that little by little I
could gradually climb right up to the knowledge of the most complex, by
assuming the same order, even among those things which do not naturally come
one after the other.
And the last was to make my calculations throughout so complete
and my review so general that I would be confident of not omitting anything.
Those long chains of reasons, all simple and easy, which geometers
have habitually used to reach their most difficult proofs gave me occasion to
imagine to myself that everything which could fall under human knowledge would
follow in the same way and that, provided only that one refused to accept anything
as true which was not and that one always kept to the order necessary to deduce
one thing from another, there could not be anything so far distant that one
could not finally reach it, nor so hidden that one could not discover it. And I
did not have much trouble finding out the issues which I had to deal with
first. For I already knew that it had to be with the simplest things, the ones
easiest to know. When I thought about how, among all those who had so far
searched for truth in the sciences, it was only the mathematicians who had been
able to find some proofs, that is to say, some certain and evident reasons, I
had no doubt at all that I should start with the same things which they had examined,
although I did not hope for any practical results, other than that they would
accustom my mind to revelling in the truth and not
remaining happy with false reasons. But for all that I did not plan trying to
learn all the particular sciences which people commonly call mathematical.
Since I saw that, even though their objects were different, they were alike in
that they all agreed they should consider nothing except the various
relationships or proportions among the objects of study found there, I thought
that it would be more valuable if I examined only these proportions in general,
without assuming that they were present in the objects, except for those which
would help to provide me knowledge of them most readily, but without in this
way restricting them at all to those objects, so that they could be all the
better applied later to every other object for which they might be suitable.
Then, because I observed that, in order to understand these things, I would
sometimes need to consider each one in particular and sometimes only to
remember them or to understand several of them together, I thought that to
consider them better separately, I ought to assume that they were like lines,
because I know of nothing simpler, nothing which I could more distinctly
represent to my imagination and my senses. But in order to remember them or to
understand several of them together, I had to explain them by some formulas as
short as possible and, by this means, I would borrow all the best elements of
analytic geometry and algebra and would correct all the defects
of one by the other.7
As a matter of fact, I venture to say that the precise observation
of these few precepts which I had selected gave me such a facility at
disentangling all the questions which these two sciences cover, that in the two
or three months that I used them to examine these questions, starting with the
simplest and the most general and letting each truth I found serve as a rule
which I could use afterwards to find others, not only did I resolve several
problems which I had previously judged very difficult, but it also seemed to me
towards the end that I could determine, even with those questions where I was ignorant,
the way to resolve them and the extent to which such resolution was possible.
In saying this, perhaps I will not appear too vain if you consider that, since
there is only one truth for each thing, whoever finds it knows as much as one
can know about it and that, for example, a child instructed in arithmetic,
having made an addition following the rules, can be confident of having found,
so far as the sum he is examining is concerned, everything that the human mind
can find out. For the method which teaches one to follow the true order and to
count exactly all the relevant details in what one is looking for contains
everything which gives certainty to the rules of arithmetic.
But what pleased me the most with this method was that with it I
was confident of using all my reason, if not perfectly, at least as well as was
in my power. In addition, I felt, as I applied it, that my mind was accustoming
itself gradually to think more clearly and distinctly about its objects, and
because I had not restricted this method to one matter in particular, I was hopeful
that I could apply it just as usefully to difficulties in the other sciences as
I had applied it to those in algebra. But for all that, I did not venture to
try immediately examining all those scientific problems which presented
themselves. For that would have been contrary to the
order which my method prescribed. But I noticed that the principles
of science all had to be borrowed from philosophy, a subject in which I no
longer found anything certain. So I thought that, before anything else, I
should attempt to establish such principles there and that, since this was the
most important matter in the world, where one had to be most fearful of
overhasty and biased judgments, I would not try to get through it until I had
reached an age considerably more mature than I was then at twenty-three and
until I had used a lot more time preparing myself, weeding out of my mind all
the bad opinions which I had accepted before that time, as well as collecting
several experiences so that later they could be the subject matter of my reasoning,
always practising the method which I had set for myself
in order to keep on improving myself in these matters.
Finally, before one starts to rebuild the lodgings where one
lives, it is not sufficient to knock them down and provide for materials and
architects or to work on the architecture oneself, having, in addition to that,
carefully drawn up a design. One must also provide oneself with some other
place where one can lodge comfortably during the time one works on the
building. Thus, in order not to be irresolute in my actions while my reason
obliged me to be so in my judgments and in order not to prevent myself living
from then on as happily as I could, I drew up for myself a provisional
morality, consisting of only three or four maxims, which I wish to share with
you.
The first was to obey the laws and the customs of my country,
constantly holding to the religion which God gave me the grace to be instructed
in since my childhood and governing myself in all other things in accordance
with the most moderate opinions, the ones furthest removed from excess, which
were commonly accepted and practised by the most
sensible of those people among whom I would be living. Since, from that point
on, I began to estimate my own views as worthless, because I wished to subject
them all to examination, I was confident that I could not do better than to
follow those of the most sensible people. And even though there might perhaps
be people just as sensible among the Persians or the Chinese as among us, it
seemed to me that the most practical thing would be for me to guide myself by
those among whom I had to live and that, in order to understand their real
opinions, it would be better for me to pay attention to what they practised rather than to what they said, not only because,
given the corruption of our morals, there are few people who are willing to
state everything they believe, but also because several are themselves ignorant
of what they believe. For the act of thinking by which one believes in
something is different from the act of thinking by which one understands that
one believes it, and one of these separate acts frequently appears without the
other. Moreover, among several opinions equally well received, I chose only the
most moderate ones, as much because such opinions are always the most
convenient to practice and probably the best, for all excess is usually bad, as
because they would also not take me as far from the true road, if I made a
mistake, as if I had chosen one of the extremes when it was the other one which
I should have followed. And I especially included among what was excessive all
promises by which one reduces one's liberty. Not that I disapprove of laws
which, in an attempt to remedy the fickleness of feeble minds, permit people
with a good plan or even an indifferent arrangement for security in business to
make vows or contracts obliging them to maintain their provisions. But because
I did not see anything in the world which remained always in the same condition
and, in my particular case, because I promised myself that I would increasingly
perfect my judgments and not make them worse, I would have thought I was
committing a great error in good sense if, because I then approved of
something, I obliged myself to continue to take it as something good later on,
when it had perhaps ceased to be so or when I had ceased to value it as something
good.
My second maxim was to be as constant and as resolute in my
actions as I could, and to follow the most doubtful opinions, once I had
settled on them for myself, with no less constancy than if they had been very
sure, imitating in this matter travelers who, finding themselves lost in some
forest, should not wander around, shifting direction this way and that; even
less should they stop in one place; they should move on always as straight as
they can in the same direction and not change it for inadequate reasons, even
though at the beginning it was perhaps only chance which led to their choice of
direction. For in this way, if they do not come out exactly where they want to,
they will at least end up arriving somewhere where they will probably be better
off than in the middle of a forest. And because the actions of life often brook
no delay, it is certainly very true that, when it is not in our power to
determine the truest opinions, we ought to follow the most probable ones, and
even when we see no difference in probability among this group of truths or
that one, nevertheless, we have to decide on some for ourselves and then to consider
them, not as something doubtful with regard to the practical matter at hand,
but as manifestly true and very certain, because the reason which made us
choose them has these qualities. This method was able from then on to relieve
me of all the regrets and remorse which usually upset the consciences of those
weak and wavering minds which permit themselves to work inconsistently with
things which they accept as good but which they later judge to be bad.
My third maxim was to try always to overcome myself rather than fortune
and to change my desires rather than the order of the world, and generally to
get in the habit of believing that there is nothing which is entirely within
our power except our thoughts, so that after we have done our best concerning
those things which lie outside of us, everything which our attempt fails to
deal with is, so far as we are concerned, absolutely impossible. That alone
seemed to me to be sufficient to prevent me from desiring anything in future
which I might not achieve and thus to make me happy. For since our will has a
natural tendency to desire only things which our understanding represents as in
some way possible, it is certain that if we think about all the good things
which are outside of us as equally distant from our power, we would no more
regret missing those whose loss appears due to our birth, when we are deprived
by no fault of our own, than we would regret not possessing the kingdoms of
China or Mexico. By making, as the saying goes, a virtue of necessity, we would
not desire health when we are sick or freedom when we are in prison, any more
than we now desire to have either a body made of some material as incorruptible
as diamonds or wings to fly, like the birds. But I admit that there is a need
for a long discipline and frequently repeated meditation in order to accustom oneself to looking at everything from this point of
view. And I believe that this is the principal secret of those philosophers who
have been able in earlier times to escape from the demands of empire and fortune
and who, despite pains and poverty, could rival their gods in happiness. For,
constantly busy thinking about the limits prescribed for them by nature, they
persuaded themselves so perfectly that nothing was in their power except their
thoughts, that that alone would be enough to prevent them from having any affection
for other things, and they acquired such an absolute control over their
thoughts that they found in that process reason to think themselves more rich
and more powerful and more free and more content than any other men, who, because
they did not possess this philosophy, never had the same control over everything
they desired, no matter how favoured they might be by
nature and fortune.
Finally, to conclude these moral precepts, I advised myself to
draw up a review of the various occupations which men have in this life, in an
attempt to make a choice about the best and, without wanting to say anything
about the others, I thought that I could not do better than to continue in the
very occupation I was engaged in, that is, using all my life to cultivate my
reason and to progress as far as I could in a knowledge of the truth, following
the method which I had prescribed for myself. I experienced such extreme contentment
once I started using this method that I did not think that one could find
anything more sweet and innocent in this life. Since every day I discovered
through this method some truths which seemed to me sufficiently important and
commonly unknown to other men, the satisfaction I got from it so filled my mind
that nothing else affected me. Moreover, the three maxims mentioned above were
founded only for the plan I had to continue my self-instruction. For since God
has given each one of us some light to distinguish truth from falsehood, I
would not have thought I could remain content with other people's opinions for
one moment, if I had not set out to use my own judgment to examine them when
the time was right, and I would not have known how to free myself from scruples
in following these opinions, if I had not hoped that I would not, in the
process, lose any opportunity to find better ones, in cases where these existed.
Finally I would not have known how to limit my desires nor how
to rest content, if I had not followed a road by which I believed I could be confident
of acquiring all the knowledge I was capable of. I thought by the same means I
could acquire all the true benefits I was capable of obtaining, all the more so
since our will tends to follow or to fly away from only those things which our
understanding has represented to it as good or bad. So in order to act well it
is sufficient to judge well, and to judge as well as one can is sufficient to
enable one to do one's best, that is, to acquire all the virtues, along with
all the other benefits which one can get, and when one is certain that that is
the case one could not fail to be content.
After assuring myself of these maxims in this manner and storing
them away, along with the truths of the faith, which have always been first in
my beliefs, I judged that, so far as all the rest of my opinions were
concerned, I could freely set about dispensing with them. Since I hoped to be
able to arrive at my goal more easily by talking with men rather than staying
any longer closed up in the room with the stove where I had had all these
thoughts, before that winter was over and done with, I set about my travels
again. And in all the nine years following I did nothing else but roll around
here and there in the world, trying to be a spectator rather than an actor in
all the comedies playing themselves out there. By reflecting on each matter, in
particular on what there was which could render it suspect and give us an
opportunity to make mistakes, I rooted out
from my mind all the errors which could have slid into it in the previous
years. Not that in the process I copied the skeptics, who doubt only for the sake
of doubting, and pretend that they are always irresolute. For my entire plan, by contrast, tended only to make me confident
about throwing away the shifting ground and the sand, in order to find the rock
or the sedimentary clay. This gave me considerable success, it
seems to me, inasmuch as in my attempts to discover the falsity or the
uncertainty of the propositions I examined, not by weak conjectures, but by
clear and confident reasoning, I came across nothing so doubtful that I did not
always draw some fairly certain conclusion from it, even if that conclusion was
that it contained nothing certain. Just as when we tear down an old lodging, we
usually keep the scrap to use in building a new structure, so, as I destroyed
all those opinions of mine which I judged poorly grounded, I made various
observations and acquired several experiences which were of use to me later in
establishing more certain ones. In addition, I continued to practice the method
which I had set for myself. For apart from the fact that I took care, in
general, to conduct all my thinking according to the rules, from time to time I
set aside a few hours which I used to apply the method to mathematical
difficulties in particular, or even to some other difficulties as well, ones
which I could frame in a manner somewhat similar to those in mathematics,
stripping from them all the principles of the other sciences which I did not
find sufficiently strong, as you will see I have done
in several which are explained in this volume.8 Thus, without
living in a way apparently different from those who have nothing else to do but
spend a sweet and innocent life studying how to separate pleasures from vices
and enjoying their leisure by making use of all honourable
entertainments without getting bored, I did not fail to follow my plans and to
benefit from the knowledge of the truth, perhaps more so than if I had only
read books or associated with men of letters.
However, these nine years passed by before I had yet taken any
stand concerning the difficulties which are usually matters of dispute among
the scholars. Nor had I started to seek the foundations of any philosophy more
reliable than common philosophy. The example of several excellent minds who had
earlier had the same idea but who, it seemed to me, had not succeeded, made me
imagine such great difficulties that I would perhaps not have ventured to undertake
it so quickly, if I had not seen that some people had already spread the rumour that I had concluded my work. I don't know what to
say about the basis for this rumour. And if I
contributed something to it by my conversations, that could have been by
confessing where I was ignorant more ingenuously than those who have studied
little are accustomed to do and perhaps also by making known the reasons I had
to doubt many things which other people considered certain, rather than by
boasting about any doctrine. But having a heart sufficiently good not to wish
people to take me for someone other than the man I am, I thought it necessary
to attempt by every means to make myself worthy of the reputation which people ascribed
to me. For exactly eight years this desire made me resolve to distance myself
from all those places where there might be people I know and to retire here, in
a country where the long duration of the war has established such order that
the armies which maintain it appear to serve only to enable the people to enjoy
the fruits of peace with even more security and where, among the crowd of a
great and very active people, who are more careful about their own affairs than
curious about those of other people, with no lack of any commodities present in
the most frequently visited towns, I was able to live retired in
solitude, just as if I were in the most isolated deserts.9
I don't know if I should share with you the first meditations
which I made there, for they are so metaphysical and so out of the ordinary
that they will perhaps not be to everyone's taste. However, in order that
people may be able to judge if the foundations which I set are sufficiently
strong, I find myself in some way compelled to speak of them. For a long time
previously I had noticed that where morals are concerned it is necessary
sometimes to follow opinions which one knows are extremely uncertain as if they
are indubitable, as mentioned above. But since at that time I wanted only to
carry out research into the truth, I thought I must do the opposite and reject
as absolutely false everything about which I could imagine the least doubt, in
order to see if there would be anything totally indisputable remaining after
that in my belief. Thus, because our senses deceive us sometimes, I was willing
to assume that there was nothing which existed the way our senses present it to
us. And because there are men who make mistakes in reasoning, even concerning
the most simple matters of geometry, and who create paralogisms,
and because I judged that I was subject to error just as much as anyone else, I
rejected as false all the reasons which I had taken earlier as proofs. Finally,
considering that all the same thoughts which we have when awake can also come
to us when we are asleep, without there being truth in any of them at the time,
I determined to pretend that everything which had ever entered my mind was no more
true than the illusions of my dreams. But immediately afterwards I noticed
that, while I wished in this way to think everything was false, it was necessary
that I—who was doing the thinking—had to be something. Noticing that this
truth—I think; therefore, I am—was so firm and so sure that all the most
extravagant assumptions of the skeptics would not be able to weaken it, I
judged that I could accept it without scruple as the first
principle of the philosophy I was looking for.10
Then I examined with attention what I was, and I saw that I could
pretend that I had no body and that the world and the place where I was did not
exist, but that, in spite of this, I could not pretend that I did not exist. By
contrast, in the very act of thinking about doubting the truth of other things,
it very clearly and certainly followed that I existed; whereas, if I had only
stopped thinking, even though all the other things which I had ever imagined
were real, I would have no reason to believe that I existed. From that I
recognized that I was a substance whose essence or nature is only thinking, a
substance which has no need of any location and does not depend on any material
thing, so that this “I,” that is to say, the soul, by which I am what I am, is
entirely distinct from the body and is even easier to know than the body, and
that, even if the body were no longer there, the soul could not help being
everything it is.
After that, I considered in general what is necessary for a
proposition to be true and certain, for since I had just found one idea which I
knew to be true and certain, I thought that I ought also to understand what
this certitude consisted of. And having noticed that in the sentence "I
think; therefore, I am" there is nothing at all to assure me that I am
speaking the truth, other than that I see very clearly that in order to think
it is necessary to exist, I judged that I could take as a general rule the
point that the things which we conceive very clearly and very distinctly are
all true. But that left the single difficulty of properly noticing which things
are the ones we conceive distinctly.
After that, I reflected on the fact that I had doubts and that, as
a result, my being was not completely perfect, for I saw clearly that it was a
greater perfection to know than to doubt. I realized that I should seek out
where I had learned to think of something more perfect than I was. And I
concluded that obviously this must be something with a nature which was, in effect,
more perfect. As for the thoughts which I had of several other things outside
of me, like the sky, the earth, light, heat, and a thousand others, I was not
worried about knowing where they came from, because I did not notice anything
in them which seemed to me to make them superior to myself. Thus, I was able to
think that, if they were true, that was because of their dependence on my
nature, in so far as it had some perfection and, if they were not true, I held
them from nothing, that is to say, that they were in me because I had some
defect. But that could not be the same with the idea of a being more perfect
than mine. For to hold that idea from nothing would be
manifestly impossible. And because it is no less unacceptable that
something more perfect should be a consequence of and dependent on something
less perfect than that something should come from nothing, I could not derive
this idea from myself. Thus, I concluded that the idea had been put in me by a
nature which was truly more perfect than I was, even one which contained in
itself all the perfections about which I could have some idea, that is to say,
to explain myself in a single phrase, a nature which was God. To this I added
the fact that, since I know about some perfections which I do not have, I was
not the only being which existed (here I will freely use, if you will permit
me, the language of the schools), but it must of necessity be the case that
there was some other more perfect being, on whom I depended and from whom I had
acquired all that I had. For if I had been alone and independent of everything
else, so that I derived from myself all perfection, no matter how small, of the
perfect being, I would have been able to have from myself, for the same reason,
all the additional perfections which I knew I lacked, and thus be myself
infinite, eternal, immutable, all knowing, all powerful, and finally have all
the perfections which I could observe as present in God. For, following the
reasoning which I have just made, to know the nature of God, to the extent that
my reasoning is able to do that, I only had to think about of all the things of
which I found some idea within me and consider whether it was a sign of perfection
to possess them or not. And I was confident that none of those ideas which
indicated some imperfection were in God, but that all the others were there,
since I perceived that doubt, inconstancy, sadness, and similar things could
not be in God, in view of the fact that I myself would have been very pleased
to be free of them. Then, in addition, I had ideas about several sensible and
corporeal things. For although I supposed that I was asleep and that everything
which I saw or imagined was false, nonetheless I could not deny that the ideas
had truly been in my thoughts. But because I had already recognized in myself
very clearly that intelligent nature is distinct from corporeal nature, when I
considered that all composite natures indicate dependency and that dependency
is manifestly a defect, I judged from this that God's perfection could not
consist of being composed of these two natures, and that thus He was not, but
that if there were some bodies in the world or even some intelligences or other
natures which were not completely perfect, their being had to depend on God's
power, in such a way as they could not subsist for a single moment without Him.
After that I wanted to look for other truths, and I proposed to
myself the subject matter of geometricians, which I understood as a continuous
body or a space extended indefinitely in length, width, and height or depth, divisible
into various parts, which could have various figures and sizes and be moved or
transposed in all sorts of ways, for the geometricians assume all that in their
subject matter. I glanced through some of their simplest proofs, and having observed
that this grand certainty which all the world attributes to them is founded
only on the fact that they plan these proofs clearly, following the rule which
I have so often stated, I notice also that there is nothing at all in their
proofs which assures me of the existence of their objects. So, for example, I
do see that, if we assume a triangle, it must be the case that its three angles
are equal to two right angles, but, in spite of that, I do not see anything
which assures me that there is a triangle in the world. But, by contrast, once
I returned to an examination of the idea which I had of a perfect being, I
found that that being contains the idea of existence in the same way as the
fact the three angles of a triangle are equal to two right angles is contained
in the idea of a triangle, or that in a sphere all the parts are equidistant
from the centre, or it is even more evident, and that, as a result, it is as
just as certain that God, this perfect being, is or exists as any geometric
proof can be.
But the reason there are several people who persuade themselves
that there are difficulties in understanding this and even knowing what their
soul is, as well, is that they never raise their minds above matters of sense
experience and that they are so accustomed not to consider anything except by
imagining it, which is a way of thinking in particular of material things, so
that everything which is not imaginable seems to them unintelligible. This
point is obvious enough in the fact that even the philosophers in the schools
maintain the axiom that there is nothing in the understanding which has not
first of all been in the senses. But it is certain that the ideas of God and
the soul have never been present in sense experience. It seemed to me that
those who want to use their imagination to understand these things are acting
just as if they want to use their eyes to hear sounds or smell odours, except that there is still this difference, that
the sense of sight provides us no less assurance of the truth of what it sees
than do the sense of smell or hearing; whereas, neither our imagination nor our
senses can assure us of anything unless our understanding intercedes.
Finally, if there are still some people who are insufficiently
persuaded of the existence of God and their soul by the reasons I have
provided, I would like them to know that everything else which they perhaps are
more confident about in their thinking, like having a body and knowing that
there are stars and an earth, and things like that, are less certain than God's
existence. For although one has a moral assurance about these things, something
which makes doubting them appear at least extravagant, nonetheless, unless one is
an unreasonable being, when a question of metaphysical certainty is involved,
one cannot deny that there is insufficient material here to make one completely
confident, for we notice that one can imagine in the same way while sleeping
that one has another body and that one sees other stars and another earth,
without such things existing. For what is the source of our knowledge that the
thoughts which come while dreaming are false, rather than the others, seeing
that often they are no less lively and distinct? And if the best minds study
this matter as much as they please, I do not think that they will be able to
give any reason which will be sufficient to remove this doubt unless they
presuppose the existence of God. First of all, the very principle which I have
so often taken as a rule—only to recognize as true all those things which we
conceive very clearly and very distinctly—is guaranteed only because of the
fact that God is or exists, that He is a perfect being, and that everything
which is in us comes from Him. From that it follows that our ideas or notions,
being real things which come from God, to the extent that they are clear and
distinct, in that respect cannot be anything but true. Consequently, if we
often enough have some ideas or notions which contain something false, that can
only be those which contain some confusion and obscurity, because in this they
participate in nothing, that is to say, they are so confused in us only because
we are not completely perfect. And it is evident that it is no less repugnant
that falsity or imperfection, in itself, should come from God than that truth
or perfection should come from nothingness. But if we did not know that
everything real and true within us comes from a perfect and infinite being,
then no matter how clear and distinct our ideas were, we would not have a
single reason to assure us that they had the perfection of being true.
Now, after the knowledge of God and the soul in this way has made
us certain of this rule, it is really easy to see that the dreams which we
imagine while asleep should not, in any way, make us doubt the truth of the
thoughts we have while awake. For if it happened, even while we were sleeping,
that we had some really distinct idea, as, for example, in the case of a geometer
inventing some new proof, the fact that he is asleep does not prevent it from
being true, and as for error, it doesn't matter that the most common dreams we
have, which consist of representing to us various objects in the same way as
our external senses do, can give us occasion to challenge the truth of such
ideas, because these ideas can also mislead us often enough without our being
asleep, as, for example, when those people suffering from jaundice see all
objects as yellow, or when the stars or other bodies at a great distant appear
to us much smaller than they are. For, finally, whether we are awake or asleep,
we should never allow ourselves to be persuaded except by the evidence of our
reason. And people should note that I say of our reason and not of our imagination
or of our senses, since even though we see the sun very clearly, we should not
for that reason judge that it is only the size which we see it, and we can
easily imagine distinctly the head of a lion mounted on the body of goat,
without having to conclude, because of that, there is a chimera in the world:
for reason does not dictate to us that what we see or imagine in this way is
true, but it does dictate to us that all our ideas or notions must have some
foundation in truth, for it would not be possible that God, who
is completely perfect and totally truthful, put them in us without that.11 Because
our reasoning is never so evident or complete during sleeping as while we are
awake, although then sometimes our imaginations are as vital or explicit, or
more so, reason also dictates to us that our ideas cannot all be true, because
we are not completely perfect—those which contain the truth must without
exception come in those we experience while awake rather than in those we have
while asleep.
I would be very pleased to continue and make you see here all the
chain of other truths which I deduced from these first ones. But because that
would require that I talked of several questions which are controversial among
scholars, things I do not want to get mixed up with, I think it would be better
to refrain from that and speak only in general about what these matters are, so
that I leave it to wiser heads to judge if it would be useful for the public to
be informed about more particular details. I have always lived firm in the
resolution that I had taken not to assume any other principle than the one
which I have just used to demonstrate the existence of God and the soul, and to
accept nothing as true which did not seem to me more clear and more certain
than the proofs of geometers had seemed to me previously. Nonetheless, I
venture to say that, not only did I find a way of satisfying myself in a short
time concerning all the difficult principles which people are accustomed to
deal with in philosophy, but also I noticed certain laws which God has established
in nature in such a way and of which he has impressed such notions in our
souls, that after we have reflected on them sufficiently, we cannot doubt that
they are precisely observed in everything which exists or which acts in the
world. Then, as I considered the consequence of these laws, it seemed to me
that I had discovered several truths more useful and more important than everything
which I had previously learned or even hoped to learn.
But since I attempted to explain the principles in a treatise
which certain considerations prevented me from publishing, I do not know how
better to make them known than stating here in summary form what that treatise
contains. Before writing that text, I had the intention of including in it all
that I thought I knew concerning the nature of material things. But just as
painters cannot portray equally well in a flat picture all the various surfaces
of a solid body and choose one of the main surfaces, which they set by itself
facing the light and, by placing the others in shadows, do not allow anything
to appear more than one can see by looking at them, in the same way, fearing
that I could not put in my discourse everything I had in my thoughts, I tried
only to reveal there fairly fully what I understood
about light, and then at the appropriate time, to add something about the sun
and the fixed stars, because almost all light comes from them, about the
heavens, because they transmit light; about the planets, comets, and the earth,
because they reflect light, and in particular about all the bodies on earth,
because they are coloured, or transparent, or luminous,
and finally about man, because he is the one who looks at these things. Even
so, in order to shade in all these things a little and to be able to speak more
freely of what I was judging, without being obliged to follow or to refute
received opinions among the scholars, I resolved to leave everyone here to
their disputes and to speak only of what would happen in a new world, if God
now created somewhere in imaginary space enough material to compose it, and if
He set in motion, in a varied and disorderly way, the various parts of this
material, so that it created a chaos as confused as poets could make it, and
then afterwards He did nothing other than lend His ordinary
help to nature and allow it to act according to the laws which He established.12 So
first of all I described this material and tried to picture it in such a way
that there is nothing in the world, it seems to me, clearer and more
intelligible, except what has been said from time to time about God and the
soul. For I even explicitly assumed that in the world there were none of those
forms or qualities which people argue about in the schools, nor, in general, anything
the knowledge of which was not so natural to our souls that we could not even
pretend to remain ignorant of it. In addition, I made known the laws of nature,
and without basing my reasoning on any principle other than the infinite
perfections of God, I tried to demonstrate all of these laws about which one
could entertain any doubts, to show that they are such that, although God could
have created several worlds, there would not be one where these failed to be
observed. After that, I showed how the greatest part of material in chaos would
have to, as a result of these laws, organize and arrange itself in a certain
way which made it similar to our heavens, how, in so doing, some of its parts
must have made up an earth and some parts planets and comets, and some other
parts a sun and fixed stars. And at this point, dwelling on the subject of
light, I explained at some length the nature of light which must be found in
the sun and the stars, how from there it crossed in an instant the immense
distances of heavenly space, and how it is reflected from the planets and
comets towards the earth. To this I added several things concerning the
material, the arrangement, the movements, and all the various qualities of
these heavens and these stars. Consequently, I thought I had said enough about
these matters to make known the fact that one observes nothing in these features
of this world which must not, or at least could not, appear entirely similar to
those of the world which I described. From there I went on to speak in
particular about the earth, about how, although I had expressly assumed that
God had placed no heaviness in the material of which it is composed, all its
parts could not help tending precisely to its centre, how, having water and air
on its surface, the arrangement of the heavens and the stars, and particularly
of the moon, had to create on earth an ebb and flow similar in all its features
to the ones we see in our oceans, and, beyond that, a certain flow in the water
as well as in the air, from east to west, like the one we also observe between
the tropics, how the mountains, seas, fountains, and rivers can naturally form
out of that, how earth's metals come into the mines, and how the plants on
earth grow in the fields, and, in general, how all the things we call mixed or
composite could be produced on earth. And, among other things, because I know
of nothing, other than the stars, which produces light except fire, I studied
to understand really clearly everything associated with the nature of fire, how
it arises, how it is nourished, how sometimes it has heat without light and sometimes
light without heat, how it can introduce various colours
in different bodies, as well as various other qualities, how it melts some
things and makes others harder, how it can consume almost everything or convert
it into ash and smoke, and finally how, out of these cinders, simply by the
violence of its actions, it makes glass. For this
transformation of cinders into glass seemed to be as wonderful as anything else
which happens in nature, and I took particular pleasure in describing it.
However, I did not want to conclude from all these things that
this world was created in the fashion which I was proposing. For it is much
more probable that God made the world from the beginning just what it had to
be. But it is certain, and this is an opinion commonly accepted among
theologians, that the actions by which God now preserves the world are exactly
the same as the method by which He created it, in such a way that even if He
did not give it at the start any form other than a chaos, providing that He had
first established the laws of nature and had given His assistance, so that it
would act as it usually does, we can believe, without denying the miracle of
creation, that because of these facts alone all purely material things would
have been able, over time, to become the way we now observe them, and their
nature is much easier to conceive when one sees them born gradually in this way than if one thinks of them only as made all at once in a
finished state.13
From the description of the inanimate bodies and of plants, I
moved onto the bodies of animals and especially the body of man. But because I
did not yet have sufficient knowledge to speak of that in the same way as of
other things, that is to say, to speak of effects in terms of causes, by
revealing the seeds and the methods by which nature had to produce them, I
contented myself with assuming that God formed the human body completely like
one of our own, both in the external shape of its limbs and in the arrangement
of its inner organs, without making them of any material other than the one
which I had described and without, at the start, placing in that body any
reasonable soul or any other thing to serve the body as a vegetative or
sensitive soul, except that He kindled in its heart one of those fires without
light which I had already explained and which I conceived as in no way
different in its nature from the fire which heats hay when it is stored before
it is dry or which makes new wines bubble when they are allowed to ferment on
the crushed grapes. For, by examining the functions which, as a result of this
assumption, could be present in this body, I found precisely all those which
could be in us without our being able to think, and thus those functions to
which our soul, that is to say, that distinct part of the body whose nature is
solely to think (as I have said above) does not contribute, functions which are
exactly the same as those in which we can say the animals without reason are
similar to us. But in doing this, I could not find any of those which, because
they are dependent on thought, are the only ones which pertain to us, to the extent
that we are men; whereas, I found all of them afterwards, once I assumed the God
had created a reasonable soul and joined it to this body in the particular way
which I described.
But so that you can see how I dealt with this material in that
treatise, I want to put in here the explanation for the movement of the heart
and the arteries, the first and the most universal thing which one observes in
animals. From that one will easily assess what one should think of all the
others. And so that people have less difficulty understanding what I am going
to say, I would like those who are not versed in anatomy to take the trouble,
before reading this, to have the heart of some large animal with lungs dissected
in front of them. For it is in all respects sufficiently similar to the heart
in man. And I would like them to have demonstrated to them the two chambers or
cavities which are in that heart. First, there is one chamber on its right
side, to which two very large tubes correspond, that is, the vena cava,
which is the principal receptacle of blood and, as it were, the trunk of the
tree of which all the other veins of the body are the branches, and the vena
arteriosa, which has, with that label, been
poorly named, because it is, in fact, an artery, the one which, originating at
the heart, divides up, after leaving the heart, into several
branches, which go out to distribute themselves throughout the lungs.14 Then
there is the chamber on the left side of the heart, to which, in the same way,
two tubes correspond, which are as large or larger than the ones just
mentioned: that is, the venous artery, which is also misnamed, because it is
nothing but a vein which comes from the lungs, where it is divided into several
branches interwoven with those from the arterial vein and with those associated
with the tube called the windpipe, through which air enters for respiration;
and the large artery which, leaving the heart, sends its branches throughout
the body. I would also like someone to point out carefully to them the eleven
small strips of skin which, just like so many small doors, open and close the
four openings in these two chambers, that is, three at the entry of the vena
cava, where they are so arranged that they cannot in any way prevent the blood
contained in the vena cava from flowing into the right chamber of the heart
and, at the same time, effectively prevent its ability to flow out; three gates
at the entry of arterial vein, which, being arranged in precisely the opposite
way, easily allow the blood in this chamber to move toward the lungs but do not
allow the blood in the lungs to return to that chamber of the heart. Then, in
the same way, there are two other strips of membrane at the opening to the
venous artery which allow the blood from the lungs to flow towards the left
chamber of the heart, but prevent its return, and there are three at the entry
of the great artery which allow blood to leave the heart but prevent it from
returning there. There is no need to seek for any reason for the number of
these membranes, beyond the fact that since the opening of the venous artery is
an oval, because of its location, it can be readily closed with two; whereas,
since the others are round, they can be more easily closed with three. In
addition, I would like people to notice that the large artery and the arterial
vein have a composition much harder and firmer than the venous artery and the
vena cava, that these last two get bigger before entering the heart and there
make a structure similar to two small sacks, called the auricles of the heart,
which are composed of flesh like that of the heart, that there is always more
heat in the heart than in any other place in the body; and finally that, if any
drop of blood enters its cavities, this heat in the heart is capable of making
the drop quickly swell and expand, just as all liquors generally do when one
lets them fall drop by drop into some really hot container.
After all that, I have no need to say anything else to explain the
movement of the heart, other than the following: when its cavities are not full
of blood, then necessarily blood flows from the vena cava into the right
chamber and from the venous artery into the left, because these two blood
vessels are always full and their openings, which are oriented towards the heart,
cannot then be blocked. But as soon as two drops of blood have entered the
heart in this way, one in each of its chambers, these drops, which could only
be of a considerable size because the openings through which they enter are
very large and the vessels they come from are really full of blood, become
thinner and expand, on account of the heat they encounter there, as a result of
which they make the entire heart expand, and then they push against and close
the five small gates which stand at the openings of the two vessels from which
these drops of blood have come, thus preventing any more blood from moving down
into the heart. And, continuing to become increasingly thinner, the drops of
blood push against and open the six other small gates which stand at the opening
of the two other vessels, through which they flow out, in this way causing all
the branches of the arterial vein and great artery to expand, almost at the
same instant as the heart, which immediately afterwards contracts, as do these
arteries as well, because the blood which has entered them gets colder again
there, and their six small gates close once more. Then the five valves on the
vena cava and the venous artery re-open, and allow passage of two more drops of
blood, which, once more, make the heart and the arteries expand, just as in the
preceding steps. And because the blood which enters the heart in this manner
passes through these two small sacks called auricles, this motion causes the
movement of the auricles to be the opposite of the heart's movement—they
contract when the heart expands. As for the rest, so that those who do not understand
the force of mathematical proofs and who are not accustomed to distinguishing
true reasons from probable reasons do not venture to deny this matter without
examining it, I wish to advise them that this movement which I have just
explained is as necessarily a result of the mere arrangement of the organs
which one can see in the heart with one's own eyes and of the heat which one
can feel there with one's fingers and of the nature of blood which one can
recognize from experience, as the movement of a clock is necessarily a result
of the force, the placement, and the shape of its counter-weights and wheels.
But if someone asks how the blood in the veins does not exhaust
itself as it flows continually into the heart in this way and how the arteries
are not overfilled because all the blood which passes through the heart goes
into them, there's no need for me to say anything in reply other than what has
already been written by an English doctor, to whom we must give the honour of having broken the ice in this area and of being
the first to teach that there are several small passages at the extremities of
the arteries through which the blood which they receive from the heart enters
into the small branches of the veins, from where it proceeds to move once again
towards the heart, so that its passage is nothing other than a
constant circulation.15 He proves this really well by the common
experience of surgeons who, having bound up an arm moderately tightly above a
place where they have opened a vein, cause the blood to flow out more
abundantly than if they had not tied the arm. And the opposite happens if they
place the binding below the cut, between the hand and the opening, or if they
make the binding above the opening very tight. For it is clear that the
binding, when moderately tight, can only prevent the blood which is already in
the arm from returning towards the heart by the veins, but in doing that the
binding does not stop the blood from continuing to flow to the place from the
arteries, because the arteries are situated below the veins and because the
skin of the arteries, being harder, is less easy to press down. Thus, the blood
which comes from the heart tends to move with more force through the arteries towards
the hand than it does in returning from the hand towards the heart through the
veins. And because this blood leaves the arm by the opening in one of the
veins, it must necessarily be the case that there are some passages below this
binding, that is to say, towards the extremities of the arm, through which it
can come there from the arteries. He [Harvey] also demonstrates really well
what he says about the flow of blood through certain small membranes which are
so arranged in various places along the veins that they do not allow blood to
move in the veins from the middle of the body towards the extremities, but only
to return from the extremities towards the heart. Moreover, he demonstrates
this by an experiment which shows that all the blood which is in the body can
leave it in a very little time by a single artery, if it is cut, even if it has
been tightly bound really close to the heart and cut between the heart and the
binding, so that one simply could not imagine any explanation other than that
the blood flowing out is coming from the heart.
But there are several other things which attest to the fact that
the true cause of this movement of blood is as I have described it. For,
firstly, the difference which one notices between the blood which comes from
the veins and the blood which flows out of the arteries could come about only
if the blood is rarefied and, as it were, distilled in passing through the
heart. It is more subtle, more lively, and warmer
immediately after leaving the heart, that is to say, in the arteries, than it
is shortly before entering the heart, that is to say, when it is in the veins.
And if one pays attention, one will find that this difference is only readily
apparent close to the heart and not so evident in places which are more distant
from it. Then, the hardness of the skins making up the arterial vein and the
large artery shows sufficiently well that the blood beats against them with
greater force than it does against the veins. And why would the left chamber of
the heart and the great artery be more ample and larger than the right chamber
and the arterial vein, if it were not for the fact that the blood of the venous
artery, which has only been in the lungs since passing through the heart, is
more subtle and more strongly and more easily rarefied than the blood which
comes immediately from the vena cava? And what could doctors diagnose by testing
the pulse, if they did not know, in keeping with the fact that blood changes
its nature, that it can be rarefied by the heat of the heart more or less
strongly and more or less quickly than before? And if one examines how this
heat is transferred to the other limbs, is it not necessary to admit that it is
by means of the blood, which, passing through the heart, is re-heated in it and
from there spreads throughout the entire body? That's the reason why, if one
takes blood from some part of the body, in that very process one takes the
heat, and even if the heart were as hot as a burning fire, it would not be sufficient
to re-heat the feet and the hands as much as it does, if it did not continually
send new blood there. From this we also understand that the true purpose of
respiration is to bring sufficient fresh air into the lungs to ensure that the
blood which comes from the right chamber of the heart, where it has been
rarefied and, as it were, changed into vapour,
thickens and changes back again into blood, before falling back into the left
chamber, without which it would not be fit to serve as nourishment for the fire
there. What confirms this is that we observe that the animals which have no
lungs also have only one cavity in the heart and that children, who cannot use
their lungs while they are closed up in their mother's womb, have an opening
through which blood flows from the vena cava into the left cavity of the heart
and a passage by which the blood comes from the arterial vein into the large
artery without passing through the lungs. Next, how would digestion take place
in the stomach, if the heart did not send heat there through the arteries and
with that some of the more easily flowing parts of the blood which help to
dissolve the food which has been sent there? And the action which converts the
juice of this food into blood—surely that is easy to understand, if one
considers that it is distilled, as it passes and re-passes through the heart,
perhaps more than one or two hundred times each day? What else do we need to
explain nutrition and the production of the various humours
in the body, other than to say that the force with which the blood, as it gets
rarefied, passes from the heart towards the extremities of the arteries, brings
it about that some portions of it stop among those parts of the limbs where
they are, and there take the place of some other parts which the blood pushes
away, and that, depending on the situation or the shape or the smallness of the
pores which these parts of blood encounter, some of them go off to certain
places rather than to others, in the same way that anyone can see with various
screens, which, being pierced in different ways, serve to separate various
grains from one another? Finally, what is most remarkable in all this is the
generation of animal spirits which resemble a very slight wind or rather a very
pure and very lively flame which, by climbing continually in great quantities
from the heart into the brain, goes from there through the nerves into the
muscles and gives movement to all the limbs, without it being necessary to
imagine any other cause which has the effect of making the most agitated and
most penetrating parts of blood, those most appropriate for making up these
animal spirits, move towards the brain rather than elsewhere, other than that
the arteries which carry these parts of the blood are those which come from the
heart toward the brain by the most direct route and that, following the laws of
mechanics, which are the same as nature's laws, when several things
collectively tend to move towards the same place where there is insufficient
room for all of them, as the parts of blood which leave the left cavity of the
heart tend towards the brain, the most feeble and less agitated parts must be
turned away from the brain by the strongest parts. In this way, only the latter
parts reach the brain.
I explained in particular detail all these things in the treatise
which I had planned to publish previously. And then I demonstrated what the
nerves and muscles in the human body must be made of, so that the animal
spirits, once inside the nerves, would have the power to move its limbs, as one
sees that heads, for a little while after being cut off, continue to move and
bite the earth, in spite of the fact that they are no longer animated. I also
showed what changes must take places in the brain to cause the waking state,
sleep, and dreams, how light, sounds, smells, tastes, heat, and all the other
qualities of external objects could imprint various ideas on the brain through
the mediation of the senses, just as hunger, thirst, and the other inner
passions can also send their ideas to the brain; what must be understood by
common sense where these ideas are taken in, by memory which preserves them,
and by fantasy which can change them in various ways and compose new ones, and,
in the same way, distribute animal spirits to the muscles and make the limbs of
the body move in all the different ways—in relation to the objects which present
themselves to the senses and in relation to the interior physical passions—just
as our bodies can move themselves without being led by the will. None of this
will seem strange to those who know how many varieties of automata,
or moving machines, human industry can make, by using only very few pieces in
comparison with the huge number of bones, muscles, nerves, arteries, veins, and
all the other parts in the body of each animal. They will look on this body as
a machine, which, having been made by the hand of God, is incomparably better
ordered and more inherently admirable in its movements than any of those which
human beings could have invented. And here, in particular, I stopped to reveal
that if there were machines which had the organs and the external shape of a
monkey or of some other animal without reason, we would have no way of
recognizing that they were not exactly the same nature as the animals; whereas,
if there was a machine shaped like our bodies which imitated our actions as
much as is morally possible, we would always have two very certain ways of
recognizing that they were not, for all their resemblance, true human beings.
The first of these is that they would never be able to use words or other signs
to make words as we do to declare our thoughts to others. For one can
easily imagine a machine made in such a way that it expresses words, even that
it expresses some words relevant to some physical actions which bring about
some change in its organs (for example, if one touches it in some spot, the machine
asks what it is that one wants to say to it; if in another spot, it cries that
one has hurt it, and things like that), but one cannot imagine a machine that
arranges words in various ways to reply to the sense of everything said in its
presence, as the most stupid human beings are capable of doing. The second test
is that, although these machines might do several things as well or perhaps
better than we do, they are inevitably lacking in some others, through which we
would discover that they act, not by knowledge, but only by the arrangement of
their organs. For, whereas reason is a universal instrument which can serve in
all sorts of encounters, these organs need some particular arrangement for each
particular action. As a result of that, it is morally impossible that there is
in a machine's organs sufficient variety to act in all the events of life in
the same way that our reason empowers us to act. Now, by these two same means,
one can also recognize the difference between human beings and beasts. For it
is really remarkable that there are no men so dull and stupid, including even
idiots, who are not capable of putting together different words and of creating
out of them a conversation through which they make their thoughts known; by
contrast, there is no other animal, no matter how perfect and how successful it
might be, which can do anything like that. And this inability does not come
about from a lack of organs For we see that magpies and parrots can emit words,
as we can, but nonetheless cannot talk the way we can, that is to say, giving
evidence that they are thinking about what they are uttering; whereas, men who
are born deaf and dumb are deprived of organs which other people use to
speak—just as much as or more than the animals—but they have a habit of
inventing on their own some signs by which they can make themselves understood
to those who, being usually with them, have the spare time to learn their language.
And this point attests not merely to the fact that animals have less reason
than men, but to the fact that they have none at all. For we see that it takes
very little for someone to learn how to speak, and since we observe inequality
among the animals of the same species just as much as among human beings, and
see that some are easier to train than others, it would be incredible that a monkey
or a parrot which was the most perfect of his species was not equivalent in
speaking to the most stupid child or at least a child with a troubled brain,
unless their soul had a nature totally different from our own. And one should
not confuse words with natural movements which attest to the passions and can
be imitated by machines as well as by animals, nor should one think, like some
ancients, that animals talk, although we do not understand their language. For
if that were true, because they have several organs related to our own, they
could just as easily make themselves understood to us as to the animals like
them. Another truly remarkable thing is that, although there are several
animals which display more industry in some of their actions than we do, we
nonetheless see that they do not display that at all in many other actions.
Thus, the fact that they do better than we do does not prove that they have a
mind, for, if that were the case, they would have more of it than any of us and
would do better in all other things; it rather shows that they have no reason
at all, and that it is nature which has activated them according to the
arrangement of their organs—just as one sees that a clock, which is composed
only of wheels and springs, can keep track of the hours and measure time more
accurately than we can, for all our care.
After that, I described the reasonable soul and revealed that it
cannot be inferred in any way from the power of matter, like the other things I
have spoken about, but that it must be expressly created, and I described how
it is not sufficient that it is lodged in the human body like a pilot in his
ship, except perhaps to move its limbs, but that it is necessary that the soul
is joined and united more closely with the body, so that it has, in addition, feelings and appetites similar to ours and thus makes up a true
human being.16 As
for the rest, here I went on at some length on the subject of the soul, because
it is among the most important. For, apart from the error of those who deny
God, which I believe I have adequately refuted above, there is nothing which
distances feeble minds from the right road of virtue more readily than to imagine
that the soul of animals is the same nature as our own and that thus we have
nothing either to fear or to hope for after this life, any more than flies and
ants do; whereas, once one knows how different they are, one understands much
better the reasons which prove that the nature of our souls is totally
independent of the body, and thus it is not at all subject to dying along with
the body. Then, to the extent that one cannot see other causes which destroy
the soul, one is naturally led to judge from that that the soul is
immortal.
It is now three years since I reached the end of the treatise
which contains all these things and since I started to revise it in order to put
it into the hands of a printer. Then I learned that people to whom I defer and
whose authority over my actions could hardly be less than my own reason over my
thoughts had expressed disapproval of an opinion about physics
published a little earlier by someone else.17 I do not
wish to say that I subscribed to that opinion, but, although I had observed in
it nothing before their censure which I could imagine prejudicial to religion
or the state, and thus nothing which would have prevented me from writing it if
reason had persuaded me, this I made me afraid that there might nonetheless be
something among my opinions where I had gone astray, notwithstanding the great
care I always took not to accept new ideas into my beliefs for which I did not
have very certain proofs and not to write anything which would work to anyone's
disadvantage. This was sufficient to oblige me to alter my resolution to
publish my opinions. For although the reasons I had adopted earlier had been
very strong, my inclination, which has always led me to hate the profession of
producing books, made me immediately find enough other reasons to excuse myself
in this matter. And, given the nature of these reasons, on one side or the
other, not only am I quite interested in stating them here, but the public may
perhaps also be interested in knowing them.
I have never made a great deal of the things which come from my
own mind, so while I gathered no other fruits from the method I was using,
other than that I satisfied myself concerning some difficulties in the
speculative sciences or else that I tried to regulate my morals by reasons
which my method taught me, I did not think myself obliged to write anything.
For where morals are concerned, every person is so full of his own good sense
that it would be possible to find as many reformers as heads, if it was
permitted to people other than those God has established as sovereigns over his
people or those to whom he has given sufficient grace and zeal to be prophets
to try changing anything in our morality. Although my speculations pleased me a
great deal, I thought that other people also had their own speculations which
pleased them perhaps even more. But immediately after I had acquired some
general notions concerning physics and, by starting to test them on various
particular difficulties, had noticed just where they could lead and how much
they differed from principles which people have used up to the present time, I
thought that I could not keep them hidden without sinning greatly against the
law which obliges us to promote as much as we can the general good of all men.
For my notions had made me see that it is possible to reach understandings
which are extremely useful for life, and that instead of the speculative
philosophy which is taught in the schools, we can find a practical philosophy
by which, through understanding the force and actions of fire, water, air,
stars, heavens, and all the other bodies which surround us as distinctly as we
understand the various crafts of our artisans, we could use them in the same
way for all applications for which they are appropriate and
thus make ourselves, as it were, the masters and possessors of nature.18 But
it was not only a desire for to invent an infinite number of devices which
might enable us to enjoy without effort the fruits of the earth and all the
commodities found in it, but mainly also my desire for the preservation of our
health, which is, without doubt, the principal benefit and the foundation of
all the other benefits in this life. For even the mind depends so much on the
temperament and the condition of the organs of the body that, if it is possible
to find some means to make human beings generally wiser and more skilful than
they have been up to this point, I believe we must seek that in medicine. It is
true that the medicine now practiced contains few things which are remarkably
useful. But without having any design to denigrate it, I am confident that
there is no one, not even those who make a living from medicine, who would not
claim that everything we know in medicine is almost nothing in comparison to
what remains to be known about it and that we could liberate ourselves from an
infinity of illnesses, both of the body and the mind, and also perhaps even of
the infirmities of ageing, if we had sufficient knowledge of their causes and
of all the remedies which nature has provided for us. Now, intending to spend
all my life in research into such a necessary science and having encountered a
road which seemed to me such that one should infallibly find this science by
following it, unless one was prevented either by the brevity of one's life or
by the lack of experiments, I judged that there was no better remedy against
these two obstacles than to communicate faithfully to the public the little I
had found and to invite good minds to try to move on further, by contributing,
each according to his own inclination and power, to the experiments which need
to be conducted and also by communicating to the public everything they learn,
so that the most recent people begin where the previous ones have finished. If
we thus joined the lives and labours of many people,
collectively we might go much further than each particular person could.
Besides, I noticed that, where experiments are concerned, they are
increasingly necessary as one's knowledge advances, for at the beginning it is
better to conduct only those which present themselves to our sense and which we
cannot ignore, provided that we engage in a little reflection, rather than to
seek out more rare and recondite experiments, because these rarer ones are
often misleading, when we do not yet know the causes of the more common phenomena,
and the circumstances on which they depend are almost always so particular and
so precise, that it is very difficult to observe them. But in this work I kept
to the following order: first, I tried to find the general principles or the
first causes of everything which exists or could exist in the world, without considering
anything germane to my purpose other than the fact that God alone created the
world, not deducing anything additional, other than certain grains of truth
which are naturally in our souls. After that, I examined what were the first
and most common effects we could deduce from these causes. By doing that, it
seems to me, I found the heavens, the stars, and earth, and even on the earth
water, air, fire, minerals, and some other things, the sort which are the most
common of all and the simplest, and thus the easiest to know. Then, when I
wanted to move down to more particular matters, so many varied ones presented
themselves to me that I did not think it would be possible for the human mind
to distinguish the forms or species of bodies on the earth from an infinity of
others which could exist there if the will of God had put them there and, thus,
that one could not adapt them to our use, unless one proceeded to the causes
through the effects and made use of several particular experiments. After that,
I turned my mind onto all the objects which had ever presented themselves to my
senses. I venture to say that I didn't notice in them anything which I could not
explain easily enough by the principles which I had found. But I must also
confess that the power of nature is so ample and vast and its principles are so
simple and so general that I observed hardly any particular effect which I did
not immediately understand as being capable of being deduced in several
different ways, so that my greatest difficulty is usually to find on which of
these ways the effect depends. In dealing with this matter, I did not know any
expedient other than, once again, to look for some experiments which would be
such that their outcomes would not be the same if one of these ways had to
explain it rather than some other way. As for the rest, I am now at a point
where I perceive well enough, it seems to me, the method one has to use to make
most of those experiments which can serve for this purpose. But I also see that
they are of such a kind and that there are so many of them that neither my
hands nor my income, even if I had a thousand times more of both than I do,
could suffice for all of them, so that from now on my progress in understanding
nature will be proportional to the means I have for conducting more or fewer
experiments. This was what I promised myself I would make known in the treatise
which I had written, as well as showing in it the practical value which the
public could gain from these experiments so clearly that I would oblige all
those who wished to promote the general well being of man, that is to say, all
those who are truly virtuous and who are not false by pretending to virtue or
merely virtuous by public opinion, to communicate to me all the experiments
which they have already made, as well as to help me in researching those which
remain to be done.
But since that time I have had other reasons which made me change my
mind and think that I really must continue to write down all matters which I
judged to have some importance, to the extent that I discovered truth in them,
and to bring to my writing the same care that I would if I wanted it published,
so that I would have more time to examine such things well, since there is no
doubt one always looks more closely at what one thinks many people must see
than at what one does only for oneself, and often matters which seemed to me
true when I began to think of them appeared false to me when I wished to put
them on paper. By writing things down, I would not lose any opportunity to
benefit the public, if I could, and, if my writings are worth anything, those
who have them after my death could use them wherever they were most relevant.
But I thought I must not, on any account, agree that they be published during
my life, so as to prevent the hostility and controversies which they could
perhaps arouse and the sort of reputation which I could acquire from giving me
any occasion to waste the time which I planned to use to instruct myself. For
although it is true that each man is obliged to provide as much as is in him
for the good of others and that there is no value whatsoever in anything which
has no benefit for anyone, nevertheless it is also true that we should care
about things more distant than the present and that it is good to forget about
things which might bring some benefit to those now living when one's intention
is to create other things which will bring more benefits to our descendants. In
fact, I really wanted people to understand that the little I had learned up to
this point is almost nothing in comparison with what I am ignorant of and what
I do not despair of being able to learn. For it is almost the same with those
who discover truth little by little in the sciences as it is with those who,
once they start to become rich, have less trouble in making large acquisitions
than they did previously, when they were poorer, in making much smaller ones.
Or, again, one can compare them to leaders of armies whose forces usually grow
in proportion to their victories and who, in order to capture towns and
provinces, need more leadership to maintain their forces after the loss of a
battle than they do after winning one. For it is truly a matter of giving
battle when one tries to overcome all the difficulties and mistakes which
prevent us from reaching an understanding of the truth. And it is a battle loss
when one accepts some false opinion concerning any matter at all general and
important. Afterwards one requires a great deal more skill to put oneself in
the same condition one was in previously than one has to have to make great
progress when one already has confirmed principles. In my case, if I have
previously found some truths in the sciences (and I hope that the matters contained
in this volume will make people conclude that I have found some), I can say
that those are only the consequences of and dependent upon five or six major
difficulties which I overcame and that I count these as so many battles in
which victory was on my side. Still, I will not hesitate to state that I think
I need to win only two or three others like those in order to reach the final
goal of my project and that I am not so advanced in years that, given the
ordinary course of nature, I still can have enough leisure to bring my project
to its conclusion. But I think that I am all the more obliged to manage the
time remaining to me, now that I have more hope of being able to use it well,
and I would, no doubt, have many chances to lose that time, if I published the
foundations of my physics. For although these foundations are almost all so
evident that one need only hear them to believe them and there are none of them
which, in my view, I cannot demonstrably prove, nevertheless, because it is
impossible that they will agree with all the various opinions of other men, I
anticipate being often distracted by the hostility they would give rise to.
One could say that this opposition would be useful, to the extent
it makes me understand my mistakes, and that, if I have anything good, others
will by this means have a more complete understanding. Since several people can
see more than one man by himself, if people begin from now on making use of my
principles, they will also help me with their inventions. But even though I recognize
that I am extremely prone to error and that I almost never have faith in the
first thoughts which come to me, nevertheless the experience which I have of
objections which people could make about me prevents me from hoping for any
benefit from such objections. For I have already undergone the criticism of so
many of those whom I held as friends and of some others who I thought
considered me indifferently and even of some in whom I knew malignity and envy
would try hard enough to uncover what affection concealed from my friends. But
it rarely happened that someone made an objection which I had not in some way
anticipated, unless it was really distant from my subject, so that I have
almost never met any critic of my opinions who did not appear to me to be less
rigorous or less fair than myself. Moreover, I have never observed that anyone
has discovered any truth of which people were previously ignorant by means of
the disputes practised in the schools. For when each
person tries to emerge victorious, people strive much harder to establish
probability than to weigh the reasons on one side or the other, and those who
have been good pleaders for a long time are not, on that account, better judges
afterwards.
As for the practical use which other people derive from the
communication of my thoughts, it could not be all that great, since I have not
taken them so far that there is no need to add a great many things before they
can be practically applied. And I think I can say without vanity that if there
is anyone who can do that, this person should be me rather than anyone else,
not because several minds incomparably better than mine could not be found in
this world, but because one cannot conceive of something so well and make it
one's own when one learns it from someone else as when one comes up with it
oneself. What is really true about this material is that, although I have often
explained some of my opinions to people with very good minds, who, while I was
talking to them, seemed to understand my opinions very clearly, nonetheless,
when they have repeated them, I have noticed that almost always they have
changed them in such a way that I could no longer admit them as mine.
Incidentally, I am more than happy to take the opportunity here to beg our
descendants never to believe anything that people will tell them comes from me,
when I never divulged them myself, and I am not astonished at the extravagant
things which people attribute to those ancient philosophers whose writing we do
not possess. I do not judge that their thoughts were really irrational on that
account, seeing that they were the best minds of their times, but merely assume
that their thoughts have been misrepresented to us. For we see also that it
almost never happens that any of their disciples surpasses them, and I am
confident that the most passionate of those people who follow Aristotle
nowadays would consider themselves fortunate if they could have as much
knowledge of nature as he had, even on condition that they would never know any
more. They are like ivy which tends not to climb higher than the trees which support it and which often even comes down
again when it has reached the tree tops. For it seems to me that those people
also come back down, that is, make themselves in some way less knowledgeable
than if they were to abandon their studying, when, not content with knowing everything
intelligibly explained by their author, they wish to find, beyond that, the
solution to several difficulties about which he has said nothing and has
perhaps never even thought. However, their way of practising
philosophy is extremely comfortable for those who have nothing but really
mediocre minds, for the obscurity of the distinctions and the principles they
use enables them to speak of everything as boldly as if they understood what
they were talking about and to defend everything that they state against the
most subtle and skillful minds, without anyone having the means to argue
against them. In this it strikes me they are similar to a blind man who, in
order to fight on equal terms against someone who can see, makes him come into
the bottom of some really obscure cave. And I can state that such people have
an interest in my abstaining from publishing the principles of philosophy I
use, because, given that they are very simple and very evident, if I published
them, I would be doing roughly the equivalent of opening some windows and
bringing the light of day into this cave where they have gone down to fight each
other. But even the best minds have no occasion to want to know these
principles. For if they want to know how to speak about everything and to acquire
the reputation of being scholarly, they will get there more easily in contenting
themselves with probability which can be found in all sorts of matters without
great trouble, rather than by seeking out the truth, which is not discovered
except little by little in some matters and which, when it is a question of
speaking of other matters, requires us to confess frankly that we are ignorant
of them. If they would rather have the undoubtedly preferable condition of
knowing a few truths over the vanity of appearing to be ignorant about nothing,
and if they wish to follow a plan similar to my own, for that they do not need
me to say anything more to them than I have already said in this discourse. For
if they are capable of moving on further than I have done, they will also, with
all the more reason, find for themselves everything I think I have found. Since
I have never looked at anything except in due order, it is certain that what
remains for me to discover is inherently more difficult and more hidden than
what I have been able to find up to this point, and they would have much less
pleasure in learning that from me than from themselves. Beyond that, the habit
they will acquire by searching first for easy things and then moving on
gradually by degrees to other more difficult things will serve them better than
all my instructions will be able to. As for me, I am convinced that if I had
been taught from my youth all the truths which I have found since my demonstrations
and if I had had no trouble in learning them, I would perhaps have never known
any others. At the very least I would never have acquired the habit and the
skill which I think I have in constantly finding new truths to the extent that
I apply myself in looking for them. In a word, if there is in the world some
work which cannot be properly completed by anyone other than the same person
who started it, it’s the work I do.
It is true that so far the experiments which can help in that work
are concerned, one man by himself is not sufficient to undertake them all. But
he cannot put to practical use hands other than his own, except those of
craftsmen or such people as he can pay, who with the hope of profit, which is a
very effective means, will carry out everything exactly as he instructs them.
As for volunteers who from curiosity or a desire to learn perhaps offer to help
him, apart from the fact that ordinarily they promise more than they deliver
and that they come up with nothing but fine propositions, none of which ever
succeeds, they inevitably want to paid with the explanation of some
difficulties or at least with compliments and useless discussions which would
cost him more time than he could afford. As for the experiments which other
people have already carried out, even though they should be willing enough to
tell him about them, those who call such experiments secrets will never do
that. Such experiments for the most part contain so many superfluous
circumstances or ingredients that it would be very difficult for him to
decipher the truth of them. Beyond that, he would find almost all of them badly
explained or even false, because those who have carried them out have forced
themselves to make the experiment appear to conform to their principles, so
that if there were some experiments he could use, once again it would not be
worth the time he would have to take up to pick them out. In the same way, if
there were in the world someone in whom people had great confidence that he was
capable of finding the greatest things and the most useful for the public as
possible, and if for this reason other men tried hard to help him in every way
to carry out his project with success, I don't see that they could do anything
for him other than to furnish the costs of the experiments he needed to carry
out, and, as to the rest, they could prevent his leisure from being taken away
by anyone's importunity. But beyond the fact that I do not presume so much of
myself as to wish to promise anything extraordinary and that I do not indulge
in thoughts so vain as to imagine to myself that the pubic ought to show a
great deal of interest in my plans, I do not have a soul so base that I would
be willing to accept from anyone a favour which
people might think I did not deserve.
All these considerations combined were the reason, three years
ago, that I did not wish to publish the treatise which I had in my hands. I
even made a resolution that during my life I would not make public any other
treatise which was so general and from which one could learn the foundations of
my physics. But, once again, there have been two other reasons since then which
have obliged me to set down here some particular essays and to give the public
some account of my actions and my plans. The first is that if I failed to do
this, several people who knew of the intention I had previously of having some
of my writing published could imagine that the reasons why I held back from
doing so were more disadvantageous to me than they were. For although I do not
like glory excessively, or, if I dare say it, although I dislike it to the extent
that I see it as contrary to peace and quiet, which I value above everything,
nonetheless I have also never tried to hide my actions as if they were crimes,
nor have I taken many precautions to remain unknown, as much because I would
have thought myself wrong if I did so, as because that would have given me a
sort of unease which would, once again, have been contrary to the perfect peace
of mind which I am looking for. Also, being always indifferently
poised between care to get known or not to get known, since I could not prevent
myself from acquiring some kind of reputation, I thought that I ought to do my
best at least to avoid having a bad one. The other reason which obliged me to
write this is that I realized more and more every day how the plan I had to
teach myself was suffering a delay, because of an infinite number of experiments
I needed and because it is impossible that I carry them out without the help of
others. Although I do not flatter myself so much as to hope that the public
pays great attention to my interests, nonetheless by the same token I do not
want to let myself down so much so that I give an excuse for those who will
come after me to reproach me some day by saying that I could have left many
things much better than I did, if I had not so neglected making them understand
the ways in which they could contribute to my project.
And I thought that it would be easy for me to chose some matters
which, without being subject to a great deal of controversy and without
requiring me to state more of my principles than I wanted to, would permit me
to reveal with sufficient clarity what I could or could not do in the sciences.
In these matters I cannot say if I have been successful, and I have no desire
to ward off anyone's criticism, as I talk in person about my own writings. But
I will be very pleased if people examine them. In order for people to have more
chances to do this, I request that all those who could have some objections
take the trouble to send them to my publisher. If he tells me about them, I
will try to attach my response to their objection and publish them at the same
time. In this way, the readers, seeing the objections and my replies together,
will judge the truth all the more easily. For I promise never to make long
replies to such objections but only to confess my errors very candidly, if I
recognize them, or else, if I cannot see them, to state simply what I believe
is required for the defence of the things I have written,
without adding there an explanation of any new material, so that I do not get
endlessly involved with one matter after another. If some of those things which
I have talked about at the beginning of On Dioptrics and On
Meteors are shocking at first, because I call them suppositions and I
do not seem to have any desire to prove them, I urge people to have the
patience to read the whole text with attention, and I hope that they will be
satisfied with it. For it seems to me that the reasons follow there in sequence
in such a way that the last ones are established by the first ones, which are
their causes, and the first ones are reciprocally established by the last ones
which are their effects. And people should not imagine that, in doing this, I
am committing the error which logicians call arguing in a circle. For since
experimentation makes most of these effects very certain, the causes which I
have deduced do not serve so much to prove these effects as to explain them, so
the case is precisely reversed: it is the causes which are proved by the
effects. And I used the name suppositions for these causes so that people might
know that I think I can deduce them from these first truths which I have explained
above but that I expressly wanted to avoid doing so, in order to prevent
certain minds who imagine that they understand in a single day everything that
another man has thought out in twenty years, as soon as he has said only two or
three words about these matters to them, and who are all the more subject to
error and less capable of truth, the more penetrating and bright they are, from
taking the opportunity to construct some extravagant philosophy on what they
believe are my principles, and in order to prevent people from attributing the
fault for that to me. As for the opinions which are entirely mine, I do not
seek to excuse them as new. To the extent that people think carefully about the
reasons for them, I am confident that they will find my opinions so simple and
so consistent with common sense that they will seem less extraordinary and less
strange than some others which people might have on the same subjects. And, in
addition, I do not boast that I am the first inventor of any of them, although
I have never accepted them merely because they were said by others or because
they have not been said by others, but simply because reason persuaded me to
accept them.
If craftsmen cannot immediately carry out the inventions explained
in the Dioptrics, I do not think that
people can, for that reason, say that the text is a poor one. For to the extent
that dexterity and skill are required to make and to adjust the machines which
I have described, without missing the slightest detail, I would be no less
amazed if they were successful on the first attempt than if someone could learn
in a single day to play the lute extremely well, simply because someone had
given him a good musical score. And if I write in French, the language of my
country, rather than in Latin, the language of my teachers, the reason is that
I hope those who use only their natural reason, pure and simple, will judge my
opinions better that those who believe nothing but ancient books. And as for
those who combine good sense with study, who are the only ones I hope to have
as my judges, I am confident that they will not be so partial to Latin that
they will refuse to listen to my reasons because I explain them in the common
language.
As for the rest, I do not wish to talk here in particular detail
about the future progress which I hope to make in the sciences, nor to commit
myself to promising the public what I am not confident of achieving. But I will
only say that I have resolved not to use the time remaining to me for anything
other than trying to acquire some knowledge of nature of such a kind that people
can derive from it rules for medicine more reliable that those which they have
at present, that my inclination keeps me so far away from all kinds of other
projects, mainly those which can be practically useful to some people only by
harming others, and that if some circumstance forced me to use my time in this
way, I do not think I would be capable of succeeding in it.
In saying this, I am making a declaration here which I well
understand cannot make me important in the world, but also I have no desire to
be important. I will always hold myself more obliged to those by whose favour I enjoy my leisure unencumbered than to those who
might offer me the most prestigious positions on earth.
1This heading does not
appear in Descartes’ text. [Back to Text]
2The word “science” in Descartes’
vocabulary means any formally organized theoretical knowledge. It does not
refer merely to the natural sciences. [Back to Text]
3The word “parricide” may
seem odd here, but it refers to acts committed against one’s own family in the
name of justice (i.e., a love of justice so strong that one is willing to kill
members of one’s own family who have done wrong). With certain pagan moralists,
such acts were considered particularly virtuous. [Back to Text]
4In 1618 Descartes, who was
Catholic, voluntarily joined the Protestant army of Maurice of Nassau, who was
active in organizing the forces of the Dutch Republic in its fight with Spain. [Back to Text]
5Ramon Llull was a thirteenth-century philosopher who wrote a
rational defence of Christianity. [Back to Text]
6Descartes’ Principia Philosophiae, 1:45-6,
discusses (in Latin) his use of these terms: “I call an idea clear (claram) when it is present and manifest to a mind
focusing on it, just as we say we perceive something clearly when it is present
to the observing eye, and stimulates it sufficiently strongly and fully. I call
an idea distinct (distinctam) which, while it
is clear, is separated and marked off from everything else in such a way that
it consists of absolutely nothing which is not clear.” It may be that Descartes
has in mind the clarity and distinctiveness of geometrical propositions. [Back to Text]
7Descartes here is referring
to his discoveries in analytic geometry, in which algebraic equations are represented
geometrically. [Back to Text]
8In the same book as
this Discourse, Descartes included sections on optics, geometry,
and meteorology. [Back to Text]
9That is, in Holland. The
“nine years” Descartes refers to earlier are 1619-1628. [Back to Text]
10In a later work this
statement “I think; therefore, I am” (je pense, donc je suis)
becomes the famous Latin sentence Cogito ergo sum. As the
subsequent lines in the discussion above indicate, this claim might be more
properly translated “I am thinking; therefore, I am,” since the certainty
remains only during the process of thinking. [Back to Text]
11A chimera is
a mythological Greek monster, made up of different animals. [Back to Text]
12Descartes is here
describing a thought experiment in which he imagines how the world might have
developed historically from material distributed randomly in the universe. The
idea is potentially dangerous because it goes against the description given in
Genesis. Hence, later on Descartes explicitly denies that he is claiming the
process he is summarizing actually took place. [Back to Text]
13Here Descartes is again
coming close to potentially dangerous speculations. To propose that God’s
actions in developing the world are subject to natural laws, even if God is the
origin of those laws, is to suggest that there are some restrictions on God’s
later actions (i.e., His interventions and actions in the world must conform to
those laws). However, the value of thinking about the development of the world
as a historical process guided by laws (rather than as the product of the
divine miracle of Creation) is that it enables human beings to come to a
rational understanding of nature and thus makes the modern scientific study of
nature possible, even if only in a thought experiment. [Back to Text]
14vena arteriosa: arterial vein, now called
the pulmonary artery. [Back
to Text]
15The English doctor is William Harvey who published his pioneering
work on the heart and circulation of the blood in 1628. [Back to Text]
16Descartes here announces the
most challenging issue arising from his views. If the body is mechanical and
the soul is not and if they must interact in some way, then how does that
interaction takes place? How can one explain consciousness in mechanistic
terms? This is still the thorniest problem in modern biology. [Back to Text]
17someone else: a
reference to Galileo, whose publication in defence of
Copernicus’ sun centered model of the solar system (in 1632) got
him into serious difficulties with the church. [Back to Text]
18In this famous statement Descartes
makes clear one of the major purposes of the new natural philosophy (science):
to gain power over nature. [Back
to Text]
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