Three years have now elapsed since I finished the treatise containing
all these matters; and I was beginning to revise it, with the view to
put it into the hands of a printer, when I learned that persons to whom
I greatly defer, and whose authority over my actions is hardly less
influential than is my own reason over my thoughts, had condemned a
certain doctrine in physics, published a short time previously by
another individual to which I will not say that I adhered, but only
that, previously to their censure I had observed in it nothing which I
could imagine to be prejudicial either to religion or to the state, and
nothing therefore which would have prevented me from giving expression
to it in writing, if reason had persuaded me of its truth; and this led
me to fear lest among my own doctrines likewise some one might be found
in which I had departed from the truth, notwithstanding the great care
I have always taken not to accord belief to new opinions of which I had
not the most certain demonstrations, and not to give expression to
aught that might tend to the hurt of any one. This has been sufficient
to make me alter my purpose of publishing them; for although the
reasons by which I had been induced to take this resolution were very
strong, yet my inclination, which has always been hostile to writing
books, enabled me immediately to discover other considerations
sufficient to excuse me for not undertaking the task. And these
reasons, on one side and the other, are such, that not only is it in
some measure my interest here to state them, but that of the public,
perhaps, to know them.
I have never made much account of what has proceeded from my own mind;
and so long as I gathered no other advantage from the method I employ
beyond satisfying myself on some difficulties belonging to the
speculative sciences, or endeavoring to regulate my actions according
to the principles it taught me, I never thought myself bound to publish
anything respecting it. For in what regards manners, every one is so
full of his own wisdom, that there might be found as many reformers as
heads, if any were allowed to take upon themselves the task of mending
them, except those whom God has constituted the supreme rulers of his
people or to whom he has given sufficient grace and zeal to be
prophets; and although my speculations greatly pleased myself, I
believed that others had theirs, which perhaps pleased them still more.
But as soon as I had acquired some general notions respecting physics,
and beginning to make trial of them in various particular difficulties,
had observed how far they can carry us, and how much they differ from
the principles that have been employed up to the present time, I
believed that I could not keep them concealed without sinning
grievously against the law by which we are bound to promote, as far as
in us lies, the general good of mankind. For by them I perceived it to
be possible to arrive at knowledge highly useful in life; and in room
of the speculative philosophy usually taught in the schools, to
discover a practical, by means of which, knowing the force and action
of fire, water, air the stars, the heavens, and all the other bodies
that surround us, as distinctly as we know the various crafts of our
artisans, we might also apply them in the same way to all the uses to
which they are adapted, and thus render ourselves the lords and
possessors of nature. And this is a result to be desired, not only in
order to the invention of an infinity of arts, by which we might be
enabled to enjoy without any trouble the fruits of the earth, and all
its comforts, but also and especially for the preservation of health,
which is without doubt, of all the blessings of this life, the first
and fundamental one; for the mind is so intimately dependent upon the
condition and relation of the organs of the body, that if any means can
ever be found to render men wiser and more ingenious than hitherto, I
believe that it is in medicine they must be sought for. It is true that
the science of medicine, as it now exists, contains few things whose
utility is very remarkable: but without any wish to depreciate it, I am
confident that there is no one, even among those whose profession it
is, who does not admit that all at present known in it is almost
nothing in comparison of what remains to be discovered; and that we
could free ourselves from an infinity of maladies of body as well as of
mind, and perhaps also even from the debility of age, if we had
sufficiently ample knowledge of their causes, and of all the remedies
provided for us by nature. But since I designed to employ my whole life
in the search after so necessary a science, and since I had fallen in
with a path which seems to me such, that if any one follow it he must
inevitably reach the end desired, unless he be hindered either by the
shortness of life or the want of experiments, I judged that there could
be no more effectual provision against these two impediments than if I
were faithfully to communicate to the public all the little I might
myself have found, and incite men of superior genius to strive to
proceed farther, by contributing, each according to his inclination and
ability, to the experiments which it would be necessary to make, and
also by informing the public of all they might discover, so that, by
the last beginning where those before them had left off, and thus
connecting the lives and labours of many, we might collectively proceed
much farther than each by himself could do.
I remarked, moreover, with respect to experiments, that they become
always more necessary the more one is advanced in knowledge; for, at
the commencement, it is better to make use only of what is
spontaneously presented to our senses, and of which we cannot remain
ignorant, provided we bestow on it any reflection, however slight, than
to concern ourselves about more uncommon and recondite phenomena: the
reason of which is, that the more uncommon often only mislead us so
long as the causes of the more ordinary are still unknown; and the
circumstances upon which they depend are almost always so special and
minute as to be highly difficult to detect. But in this I have adopted
the following order: first, I have essayed to find in general the
principles, or first causes of all that is or can be in the world,
without taking into consideration for this end anything but God himself
who has created it, and without educing them from any other source than
from certain germs of truths naturally existing in our minds In the
second place, I examined what were the first and most ordinary effects
that could be deduced from these causes; and it appears to me that, in
this way, I have found heavens, stars, an earth, and even on the earth
water, air, fire, minerals, and some other things of this kind, which
of all others are the most common and simple, and hence the easiest to
know. Afterwards when I wished to descend to the more particular, so
many diverse objects presented themselves to me, that I believed it to
be impossible for the human mind to distinguish the forms or species of
bodies that are upon the earth, from an infinity of others which might
have been, if it had pleased God to place them there, or consequently
to apply them to our use, unless we rise to causes through their
effects, and avail ourselves of many particular experiments. Thereupon,
turning over in my mind I the objects that had ever been presented to
my senses I freely venture to state that I have never observed any
which I could not satisfactorily explain by the principles had
discovered. But it is necessary also to confess that the power of
nature is so ample and vast, and these principles so simple and
general, that I have hardly observed a single particular effect which I
cannot at once recognize as capable of being deduced in man different
modes from the principles, and that my greatest difficulty usually is
to discover in which of these modes the effect is dependent upon them;
for out of this difficulty cannot otherwise extricate myself than by
again seeking certain experiments, which may be such that their result
is not the same, if it is in the one of these modes at we must explain
it, as it would be if it were to be explained in the other. As to what
remains, I am now in a position to discern, as I think, with sufficient
clearness what course must be taken to make the majority those
experiments which may conduce to this end: but I perceive likewise that
they are such and so numerous, that neither my hands nor my income,
though it were a thousand times larger than it is, would be sufficient
for them all; so that according as henceforward I shall have the means
of making more or fewer experiments, I shall in the same proportion
make greater or less progress in the knowledge of nature. This was what
I had hoped to make known by the treatise I had written, and so clearly
to exhibit the advantage that would thence accrue to the public, as to
induce all who have the common good of man at heart, that is, all who
are virtuous in truth, and not merely in appearance, or according to
opinion, as well to communicate to me the experiments they had already
made, as to assist me in those that remain to be made.
But since that time other reasons have occurred to me, by which I have
been led to change my opinion, and to think that I ought indeed to go
on committing to writing all the results which I deemed of any moment,
as soon as I should have tested their truth, and to bestow the same
care upon them as I would have done had it been my design to publish
them. This course commended itself to me, as well because I thus
afforded myself more ample inducement to examine them thoroughly, for
doubtless that is always more narrowly scrutinized which we believe
will be read by many, than that which is written merely for our private
use (and frequently what has seemed to me true when I first conceived
it, has appeared false when I have set about committing it to writing),
as because I thus lost no opportunity of advancing the interests of the
public, as far as in me lay, and since thus likewise, if my writings
possess any value, those into whose hands they may fall after my death
may be able to put them to what use they deem proper. But I resolved by
no means to consent to their publication during my lifetime, lest
either the oppositions or the controversies to which they might give
rise, or even the reputation, such as it might be, which they would
acquire for me, should be any occasion of my losing the time that I had
set apart for my own improvement. For though it be true that every one
is bound to promote to the extent of his ability the good of others,
and that to be useful to no one is really to be worthless, yet it is
likewise true that our cares ought to extend beyond the present, and it
is good to omit doing what might perhaps bring some profit to the
living, when we have in view the accomplishment of other ends that will
be of much greater advantage to posterity. And in truth, I am quite
willing it should be known that the little I have hitherto learned is
almost nothing in comparison with that of which I am ignorant, and to
the knowledge of which I do not despair of being able to attain; for it
is much the same with those who gradually discover truth in the
sciences, as with those who when growing rich find less difficulty in
making great acquisitions, than they formerly experienced when poor in
making acquisitions of much smaller amount. Or they may be compared to
the commanders of armies, whose forces usually increase in proportion
to their victories, and who need greater prudence to keep together the
residue of their troops after a defeat than after a victory to take
towns and provinces. For he truly engages in battle who endeavors to
surmount all the difficulties and errors which prevent him from
reaching the knowledge of truth, and he is overcome in fight who admits
a false opinion touching a matter of any generality and importance, and
he requires thereafter much more skill to recover his former position
than to make great advances when once in possession of thoroughly
ascertained principles. As for myself, if I have succeeded in
discovering any truths in the sciences (and I trust that what is
contained in this volume I will show that I have found some), I can
declare that they are but the consequences and results of five or six
principal difficulties which I have surmounted, and my encounters with
which I reckoned as battles in which victory declared for me. I will
not hesitate even to avow my belief that nothing further is wanting to
enable me fully to realize my designs than to gain two or three similar
victories; and that I am not so far advanced in years but that,
according to the ordinary course of nature, I may still have sufficient
leisure for this end. But I conceive myself the more bound to husband
the time that remains the greater my expectation of being able to
employ it aright, and I should doubtless have much to rob me of it,
were I to publish the principles of my physics: for although they are
almost all so evident that to assent to them no more is needed than
simply to understand them, and although there is not one of them of
which I do not expect to be able to give demonstration, yet, as it is
impossible that they can be in accordance with all the diverse opinions
of others, I foresee that I should frequently be turned aside from my
grand design, on occasion of the opposition which they would be sure to
awaken.
It may be said, that these oppositions would be useful both in making
me aware of my errors, and, if my speculations contain anything of
value, in bringing others to a fuller understanding of it; and still
farther, as many can see better than one, in leading others who are now
beginning to avail themselves of my principles, to assist me in turn
with their discoveries. But though I recognize my extreme liability to
error, and scarce ever trust to the first thoughts which occur to me,
yet-the experience I have had of possible objections to my views
prevents me from anticipating any profit from them. For I have already
had frequent proof of the judgments, as well of those I esteemed
friends, as of some others to whom I thought I was an object of
indifference, and even of some whose malignancy and envy would, I knew,
determine them to endeavor to discover what partiality concealed from
the eyes of my friends. But it has rarely happened that anything has
been objected to me which I had myself altogether overlooked, unless it
were something far removed from the subject: so that I have never met
with a single critic of my opinions who did not appear to me either
less rigorous or less equitable than myself. And further, I have never
observed that any truth before unknown has been brought to light by the
disputations that are practised in the schools; for while each strives
for the victory, each is much more occupied in making the best of mere
verisimilitude, than in weighing the reasons on both sides of the
question; and those who have been long good advocates are not
afterwards on that account the better judges.
As for the advantage that others would derive from the communication of
my thoughts, it could not be very great; because I have not yet so far
prosecuted them as that much does not remain to be added before they
can be applied to practice. And I think I may say without vanity, that
if there is any one who can carry them out that length, it must be
myself rather than another: not that there may not be in the world many
minds incomparably superior to mine, but because one cannot so well
seize a thing and make it one’s own, when it has been learned from
another, as when one has himself discovered it. And so true is this of
the present subject that, though I have often explained some of my
opinions to persons of much acuteness, who, whilst I was speaking,
appeared to understand them very distinctly, yet, when they repeated
them, I have observed that they almost always changed them to such an
extent that I could no longer acknowledge them as mine. I am glad, by
the way, to take this opportunity of requesting posterity never to
believe on hearsay that anything has proceeded from me which has not
been published by myself; and I am not at all astonished at the
extravagances attributed to those ancient philosophers whose own
writings we do not possess; whose thoughts, however, I do not on that
account suppose to have been really absurd, seeing they were among the
ablest men of their times, but only that these have been falsely
represented to us. It is observable, accordingly, that scarcely in a
single instance has any one of their disciples surpassed them; and I am
quite sure that the most devoted of the present followers of Aristotle
would think themselves happy if they had as much knowledge of nature as
he possessed, were it even under the condition that they should never
afterwards attain to higher. In this respect they are like the ivy
which never strives to rise above the tree that sustains it, and which
frequently even returns downwards when it has reached the top; for it
seems to me that they also sink, in other words, render themselves less
wise than they would be if they gave up study, who, not contented with
knowing all that is intelligibly explained in their author, desire in
addition to find in him the solution of many difficulties of which he
says not a word, and never perhaps so much as thought. Their fashion of
philosophizing, however, is well suited to persons whose abilities fall
below mediocrity; for the obscurity of the distinctions and principles
of which they make use enables them to speak of all things with as much
confidence as if they really knew them, and to defend all that they say
on any subject against the most subtle and skillful, without its being
possible for any one to convict them of error. In this they seem to me
to be like a blind man, who, in order to fight on equal terms with a
person that sees, should have made him descend to the bottom of an
intensely dark cave: and I may say that such persons have an interest
in my refraining from publishing the principles of the philosophy of
which I make use; for, since these are of a kind the simplest and most
evident, I should, by publishing them, do much the same as if I were to
throw open the windows, and allow the light of day to enter the cave
into which the combatants had descended. But even superior men have no
reason for any great anxiety to know these principles, for if what they
desire is to be able to speak of all things, and to acquire a
reputation for learning, they will gain their end more easily by
remaining satisfied with the appearance of truth, which can be found
without much difficulty in all sorts of matters, than by seeking the
truth itself which unfolds itself but slowly and that only in some
departments, while it obliges us, when we have to speak of others,
freely to confess our ignorance. If, however, they prefer the knowledge
of some few truths to the vanity of appearing ignorant of none, as such
knowledge is undoubtedly much to be preferred, and, if they choose to
follow a course similar to mine, they do not require for this that I
should say anything more than I have already said in this discourse.
For if they are capable of making greater advancement than I have made,
they will much more be able of themselves to discover all that I
believe myself to have found; since as I have never examined aught
except in order, it is certain that what yet remains to be discovered
is in itself more difficult and recondite, than that which I have
already been enabled to find, and the gratification would be much less
in learning it from me than in discovering it for themselves. Besides
this, the habit which they will acquire, by seeking first what is easy,
and then passing onward slowly and step by step to the more difficult,
will benefit them more than all my instructions. Thus, in my own case,
I am persuaded that if I had been taught from my youth all the truths
of which I have since sought out demonstrations, and had thus learned
them without labour, I should never, perhaps, have known any beyond
these; at least, I should never have acquired the habit and the
facility which I think I possess in always discovering new truths in
proportion as I give myself to the search. And, in a single word, if
there is any work in the world which cannot be so well finished by
another as by him who has commenced it, it is that at which I labour.
It is true, indeed, as regards the experiments which may conduce to
this end, that one man is not equal to the task of making them all; but
yet he can advantageously avail himself, in this work, of no hands
besides his own, unless those of artisans, or parties of the same kind,
whom he could pay, and whom the hope of gain (a means of great
efficacy) might stimulate to accuracy in the performance of what was
prescribed to them. For as to those who, through curiosity or a desire
of learning, of their own accord, perhaps, offer him their services,
besides that in general their promises exceed their performance, and
that they sketch out fine designs of which not one is ever realized,
they will, without doubt, expect to be compensated for their trouble by
the explication of some difficulties, or, at least, by compliments and
useless speeches, in which he cannot spend any portion of his time
without loss to himself. And as for the experiments that others have
already made, even although these parties should be willing of
themselves to communicate them to him (which is what those who esteem
them secrets will never do), the experiments are, for the most part,
accompanied with so many circumstances and superfluous elements, as to
make it exceedingly difficult to disentangle the truth from its
adjuncts--besides, he will find almost all of them so ill described, or
even so false (because those who made them have wished to see in them
only such facts as they deemed conformable to their principles), that,
if in the entire number there should be some of a nature suited to his
purpose, still their value could not compensate for the time what would
be necessary to make the selection. So that if there existed any one
whom we assuredly knew to be capable of making discoveries of the
highest kind, and of the greatest possible utility to the public; and
if all other men were therefore eager by all means to assist him in
successfully prosecuting his designs, I do not see that they could do
aught else for him beyond contributing to defray the expenses of the
experiments that might be necessary; and for the rest, prevent his
being deprived of his leisure by the unseasonable interruptions of any
one. But besides that I neither have so high an opinion of myself as to
be willing to make promise of anything extraordinary, nor feed on
imaginations so vain as to fancy that the public must be much
interested in my designs; I do not, on the other hand, own a soul so
mean as to be capable of accepting from any one a favor of which it
could be supposed that I was unworthy.
These considerations taken together were the reason why, for the last
three years, I have been unwilling to publish the treatise I had on
hand, and why I even resolved to give publicity during my life to no
other that was so general, or by which the principles of my physics
might be understood. But since then, two other reasons have come into
operation that have determined me here to subjoin some particular
specimens, and give the public some account of my doings and designs.
Of these considerations, the first is, that if I failed to do so, many
who were cognizant of my previous intention to publish some writings,
might have imagined that the reasons which induced me to refrain from
so doing, were less to my credit than they really are; for although I
am not immoderately desirous of glory, or even, if I may venture so to
say, although I am averse from it in so far as I deem it hostile to
repose which I hold in greater account than aught else, yet, at the
same time, I have never sought to conceal my actions as if they were
crimes, nor made use of many precautions that I might remain unknown;
and this partly because I should have thought such a course of conduct
a wrong against myself, and partly because it would have occasioned me
some sort of uneasiness which would again have been contrary to the
perfect mental tranquillity which I court. And forasmuch as, while thus
indifferent to the thought alike of fame or of forgetfulness, I have
yet been unable to prevent myself from acquiring some sort of
reputation, I have thought it incumbent on me to do my best to save
myself at least from being ill-spoken of. The other reason that has
determined me to commit to writing these specimens of philosophy is,
that I am becoming daily more and more alive to the delay which my
design of self-instruction suffers, for want of the infinity of
experiments I require, and which it is impossible for me to make
without the assistance of others: and, without flattering myself so
much as to expect the public to take a large share in my interests, I
am yet unwilling to be found so far wanting in the duty I owe to
myself, as to give occasion to those who shall survive me to make it
matter of reproach against me some day, that I might have left them
many things in a much more perfect state than I have done, had I not
too much neglected to make them aware of the ways in which they could
have promoted the accomplishment of my designs.
And I thought that it was easy for me to select some matters which
should neither be obnoxious to much controversy, nor should compel me
to expound more of my principles than I desired, and which should yet
be sufficient clearly to exhibit what I can or cannot accomplish in the
sciences. Whether or not I have succeeded in this it is not for me to
say; and I do not wish to forestall the judgments of others by speaking
myself of my writings; but it will gratify me if they be examined, and,
to afford the greater inducement to this I request all who may have any
objections to make to them, to take the trouble of forwarding these to
my publisher, who will give me notice of them, that I may endeavor to
subjoin at the same time my reply; and in this way readers seeing both
at once will more easily determine where the truth lies; for I do not
engage in any case to make prolix replies, but only with perfect
frankness to avow my errors if I am convinced of them, or if I cannot
perceive them, simply to state what I think is required for defense of
the matters I have written, adding thereto no explication of any new
matte that it may not be necessary to pass without end from one thing
to another.
If some of the matters of which I have spoken in the beginning of the
“Dioptrics” and “Meteorics” should offend at first sight, because I
call them hypotheses and seem indifferent about giving proof of them, I
request a patient and attentive reading of the whole, from which I hope
those hesitating will derive satisfaction; for it appears to me that
the reasonings are so mutually connected in these treatises, that, as
the last are demonstrated by the first which are their causes, the
first are in their turn demonstrated by the last which are their
effects. Nor must it be imagined that I here commit the fallacy which
the logicians call a circle; for since experience renders the majority
of these effects most certain, the causes from which I deduce them do
not serve so much to establish their reality as to explain their
existence; but on the contrary, the reality of the causes is
established by the reality of the effects. Nor have I called them
hypotheses with any other end in view except that it may be known that
I think I am able to deduce them from those first truths which I have
already expounded; and yet that I have expressly determined not to do
so, to prevent a certain class of minds from thence taking occasion to
build some extravagant philosophy upon what they may take to be my
principles, and my being blamed for it. I refer to those who imagine
that they can master in a day all that another has taken twenty years
to think out, as soon as he has spoken two or three words to them on
the subject; or who are the more liable to error and the less capable
of perceiving truth in very proportion as they are more subtle and
lively. As to the opinions which are truly and wholly mine, I offer no
apology for them as new,--persuaded as I am that if their reasons be
well considered they will be found to be so simple and so conformed, to
common sense as to appear less extraordinary and less paradoxical than
any others which can be held on the same subjects; nor do I even boast
of being the earliest discoverer of any of them, but only of having
adopted them, neither because they had nor because they had not been
held by others, but solely because reason has convinced me of their
truth.
Though artisans may not be able at once to execute the invention which
is explained in the “Dioptrics,” I do not think that any one on that
account is entitled to condemn it; for since address and practice are
required in order so to make and adjust the machines described by me as
not to overlook the smallest particular, I should not be less
astonished if they succeeded on the first attempt than if a person were
in one day to become an accomplished performer on the guitar, by merely
having excellent sheets of music set up before him. And if I write in
French, which is the language of my country, in preference to Latin,
which is that of my preceptors, it is because I expect that those who
make use of their unprejudiced natural reason will be better judges of
my opinions than those who give heed to the writings of the ancients
only; and as for those who unite good sense with habits of study, whom
alone I desire for judges, they will not, I feel assured, be so partial
to Latin as to refuse to listen to my reasonings merely because I
expound them in the vulgar tongue.
In conclusion, I am unwilling here to say anything very specific of the
progress which I expect to make for the future in the sciences, or to
bind myself to the public by any promise which I am not certain of
being able to fulfill; but this only will I say, that I have resolved
to devote what time I may still have to live to no other occupation
than that of endeavoring to acquire some knowledge of Nature, which
shall be of such a kind as to enable us therefrom to deduce rules in
medicine of greater certainty than those at present in use; and that my
inclination is so much opposed to all other pursuits, especially to
such as cannot be useful to some without being hurtful to others, that
if, by any circumstances, I had been constrained to engage in such, I
do not believe that I should have been able to succeed. Of this I here
make a public declaration, though well aware that it cannot serve to
procure for me any consideration in the world, which, however, I do not
in the least affect; and I shall always hold myself more obliged to
those through whose favor I am permitted to enjoy my retirement without
interruption than to any who might offer me the highest earthly
preferments.