___________________________________________________
Rene Descartes
Discourse on the Method for Reasoning
Well and for Seeking Truth in the Sciences
___________________________________________________
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.
(1) This heading does
not appear in Descartes’ text. [Back to
Text]
(2) The word “science”
in Descartes’ vocabulary means any formally organized theoretical knowledge. It
does not refer merely to the natural sciences. [Back to Text]
(3) The 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]
(4) In 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]
(5) Ramon Llull was a thirteenth-century philosopher who wrote a
rational defence of Christianity. [Back
to Text]
(6) Descartes’ 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]
(7) Descartes here is
referring to his discoveries in analytic geometry, in which algebraic equations
are represented geometrically. [Back to
Text]
(8) In the same book as
this Discourse, Descartes included sections on optics, geometry,
and meteorology. [Back to Text]
(9) That is, in Holland.
The “nine years” Descartes refers to earlier are 1619-1628. [Back to
Text]
(10) In 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]
(11) A chimera is
a mythological Greek monster, made up of different animals. [Back
to Text]
(12) Descartes 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]
(13) Here 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]
(14)
vena arteriosa: arterial vein, now called the pulmonary
artery. [Back to Text]
(15) The English doctor is William Harvey who
published his pioneering work on the heart and circulation of the blood in
1628. [Back
to Text]
(16) Descartes 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]
(17)
someone 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]
(18) In 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]