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 1 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.
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