یکشنبه ۲۵ شهریور ۰۳ | ۱۳:۳۳ ۷ بازديد
remarkable thing about all this is the generation of animal
spirits,* which, like a very subtle* wind, or rather like a very pure
and living flame, rise continually in great abundance from the
heart to the brain, pass from there through the nerves into the
muscles, and impart movement to all our members. We do
not need to suppose any other cause to impel the most agi-
tated and the most penetrating parts of the blood (and hence
the best suited to compose these spirits) to make their way to
the brain rather than anywhere else, than that the arteries that
carry them there are those which come most directly from the
heart, and that, according to the rules of mechanics (which
are the same as those of nature), when many things tend to
move together towards the same place in which there is not
room for them all (as in the case of the parts of the blood that
leave the left cavity of the heart and flow towards the brain),
the weaker or less agitated must of necessity be displaced by
the stronger, which by this means reach their destination on
their own.
I had explained all these matters in considerable detail in
the treatise which I had earlier intended to publish.* And I
had then shown what structure the nerves and the muscles of
the human body must have to enable the animal spirits, being
inside that body, to have the power to move its members, as we
observe in the case of severed heads, which we can see moving
and biting the earth shortly after having been cut off, although
they are no longer animate. I had also shown what changes
must occur in the brain to cause states of waking, sleeping,
and dreaming; how light, sounds, smells, tastes, heat, and all
the other qualities of external objects can imprint various ideas
on the brain through the intermediary of the senses; how
hunger, thirst, and the other internal passions can also transmit
ideas to the brain; what must be taken to be the sensus com-
munis* in which these are received, the memory which pre-
serves them, and the faculty of imagination, which can change
them in different ways, form them into new ideas and, by the
the members of this body move, with respect both to the
objects which present themselves to the senses and to the
internal passions, in as many different ways as the parts of our
bodies can move without being directed by our will. This will
not appear at all strange to those who know how wide a range
of different automata or moving machines the skill of man can
make using only very few parts, in comparison to the great
number of bones, muscles, nerves, arteries, veins, and all the
other parts which are in the body of every animal. For they
will consider this body as a machine which, having been made
by the hand of God, is incomparably better ordered and has in
itself more amazing movements than any that can be created
by men.
At this point I had dwelt on this issue to show that if there
were such machines having the organs and outward shape of a
monkey or any other irrational animal, we would have no
means of knowing that they were not of exactly the same
nature as these animals, whereas, if any such machines
resembled us in body and imitated our actions insofar as this
was practically possible, we should still have two very certain
means of recognizing that they were not, for all that, real
human beings.* The first is that they would never be able to use
words or other signs by composing them as we do to declare
our thoughts to others. For we can well conceive of a machine
made in such a way that it emits words, and even utters them
about bodily actions which bring about some corresponding
change in its organs (if, for example, we touch it on a given
spot, it will ask what we want of it; or if we touch it somewhere
else, it will cry out that we are hurting it, and so on); but it is
not conceivable that it should put these words in different
orders to correspond to the meaning of things said in its pres-
ence, as even the most dull-witted of men can do. And the
second means is that, although such machines might do many
things as well or even better than any of us, they would inevit-
ably fail to do some others, by which we would discover that
were disposed in a certain way. For, whereas reason is a uni-
versal instrument which can operate in all sorts of situations,
their organs have to have a particular disposition for each par-
ticular action, from which it follows that it is practically
impossible for there to be enough different organs in a
machine to cause it to act in all of life’s occurrences in the same
way that our reason causes us to act.
Now we can also determine the difference between men and
animals by these two means. For it is a very remarkable fact
that there are no men so dull-witted and stupid, not even
madmen, that they are incapable of stringing together differ-
ent words, and composing them into utterances, through
which they let their thoughts be known; and, conversely, there
is no other animal, no matter how perfect and well endowed by
birth it may be, that can do anything similar. Nor does this
arise from lack of organs, for we can see that magpies and
parrots can utter words as we do, and yet cannot speak like us,
that is, by showing that they are thinking what they are saying;
whereas men born deaf and dumb, who are deprived as much
as, or more than, animals of the organs which in others serve
for speech, usually invent certain signs to make themselves
understood by those who are their habitual companions and
have the time to learn their language. This shows not only that
animals have less reason than man, but that they have none at
all.* For it is clear that we need very little reason in order to be
able to speak; and given that as much inequality is found
among animals of the same species as among men, and that
some are easier to train than others, it is unbelievable that the
most perfect monkey or parrot of their species should not be
able to speak as well as the most stupid child, or at least a child
with a disturbed brain, unless their soul were of a wholly dif-
ferent nature to ours. And speech must not be confused with
the natural movements that are signs of passion and can be
imitated by machines as well by as animals; neither must one
imagine, as did certain ancient thinkers, that animals speak,
true, they would be able to make themselves understood by us
as well as by other members of their species, since they have
many organs that correspond to ours. It is also a very remark-
able fact that although many animals show more skill in some
of their actions than we correspondingly do, it is nonetheless
clear than the same animals show none at all in many others, so
that what they can do better than us does not prove that they
have any mental powers, for it would follow from this that they
would have more intelligence than any of us, and would sur-
pass us in everything. Rather, it shows that they have no men-
tal powers whatsoever, and that it is nature which acts in them,
according to the disposition of their organs; just as we see that
a clock consisting only of ropes and springs can count the
hours and measure time more accurately than we can in spite
of all our wisdom.
Following this, I had described the rational soul, and shown
that, unlike the other things of which I had spoken, it could
not possibly be derived from the potentiality of matter, but
that it must have been created expressly. And I had shown
how it is not sufficient for it to be lodged in the human body
like a pilot in his ship,* except perhaps to move its members,
but that it needs to be more closely joined and united with the
body in order to have, in addition, feelings* and appetites like
the ones we have, and in this way compose a true man. I dwelt
a little at this point on the subject of the soul, because it is of
the greatest importance. For, after the error of those who deny
the existence of God, which I believe I have adequately
refuted above, there is none which causes weak minds to stray
more readily from the narrow path of virtue than that of
imagining that the souls of animals are of the same nature as
our own, and that, as a consequence, we have nothing more to
fear or to hope for after this present life, any more than flies
and ants. But when we know how different flies and ants are,
we can understand much better the arguments which prove
that our soul is of a nature entirely independent of the body,
body is. And given that we cannot see any other causes which
may destroy the soul, we are naturally led to conclude that it
is immortal.*
It is now three years since I completed the treatise that
contained all the above. I was beginning to revise it so that I
could place it in the hands of a printer, when I learned that
persons to whom I defer, and whose authority holds hardly less
sway over my actions than my own reason over my thoughts,
had condemned a physical theory, published a little earlier by
someone else,* to which I would not want to go so far as to say I
subscribed, but only that I had seen nothing in it before their
act of censure which I could imagine being prejudicial to
religion or state, and which consequently would have pre-
vented me from writing about it, if my reason had persuaded
me to do so. This made me fear that there might be one of my
own opinions in which I was equally mistaken, notwithstand-
ing the great care I have always taken never to accept any new
opinions for which I did not have very certain proof, and not to
write about any which might work to the disadvantage of any-
one. This was enough to make me change the decision I had
taken to publish my theories. For even if the reasons for taking
the decision earlier to publish were very strong, my natural
inclination, which has always made me dislike the business*
of writing books, led me to find a host of other reasons for
excusing myself from doing so. And these reasons, both for
and against, are such that not only do I have some interest
in declaring them here, but the public may also have some
interest in knowing what they are.
I have never laid great store by the products of my mind,
and as long as I reaped no other benefits from the method that
I use (apart from satisfying myself about some problems that
belong to the speculative sciences, or trying to direct my life by
the precepts that it inculcated in me), I have not felt obliged to
write anything about it. For as far as mode of life is concerned,
everyone is so sure that they know best that one could find as
other than those whom God has established as sovereigns over
their peoples, or those to whom He has given sufficient grace
and zeal to be prophets, to set about changing anything. And
although I was very pleased with my speculations, I believed
that others had their own which perhaps pleased them even
more. But having no sooner acquired some general notions
about physics, and begun to test them out on various particular
problems, I noticed where they may lead and how much they
differ from the principles that have been employed up to now,
and I believed that I could not keep them hidden without
sinning greatly against the law that obliges us to procure, as far
as it is in our power, the general good of all mankind. For these
notions have made me see that it is possible to attain know-
ledge which is very useful in life, and that unlike the specula-
tive philosophy that is taught in the schools, it can be turned
into a practice by which, knowing the power and action of fire,
water, air, stars, the heavens, and all the other bodies that are
around us as distinctly as we know the different trades of our
craftsmen, we could put them to all the uses for which they are
suited and thus make ourselves as it were the masters and
possessors of nature.* This is not only desirable for the dis-
covery of a host of inventions which will lead us effortlessly to
enjoy the fruits of the earth and all the commodities that can
be found in it, but principally also for the preservation of
health, which is without doubt the highest good and the foun-
dation of all the other goods of this life. For even the mind
depends so much on the temperament* and disposition of the
organs of the body that, if it is possible to find some way of
making men in most cases wiser and more skilful than they
have been hitherto, I believe that it is in medicine that it must
be sought. It is true that medicine as presently practised con-
tains little of such notable benefit; but without wishing to dis-
parage it, I am certain that there is no one, even among those
whose profession it is, who will not admit that what is known
about it is almost nothing compared to what remains to be
illnesses of both body and mind, and perhaps even the decline
of old age, if we knew enough about their causes and the
remedies with which nature has provided us.* So, intending to
devote my whole life to the pursuit of such an indispensable
branch of knowledge, and having found a path which, I think,
will inevitably lead me to it, unless prevented from doing so by
the brevity of life or the lack of empirical information, I judged
that there was no better remedy against these two obstacles
than to communicate faithfully to the public what little I had
discovered, and to urge good minds to try to go further by
contributing, each according to his inclinations and power, to
the observations and experiments* that need to be undertaken,
and by communicating in turn to the public everything that
they learn. Thus, as the last would start from where their
predecessors had left off, thereby combining the lives and
labours of many, we might together make much greater
progress than any one man could make on his own.
I noted, moreover, in respect of observations and experi-
ments, that the further we progress in knowledge the more
necessary they become. For, at the beginning, rather than to
seek out rarer and more contrived experiments, it is better to
undertake only those which communicate themselves directly
to our senses, of which we cannot remain ignorant, provided
that we reflect a little on them. The reason for this is that rarer
experiments often mislead us, at a time when we do not still
know the causes of more common ones, and the circumstances
on which they depend are nearly always so specific* and minute
that it is difficult to take good note of them. But the order to
which I have adhered in this regard is the following. First, I
have tried to find in general the principles or first causes of
everything that exists or can exist the world, without consider-
ing to this end anything other than God alone, who has created
it, and deriving these principles only from certain seeds of
truths which are naturally in our souls. After that, I came to
examine what are the first and most common effects which one
this way discovered the heavens, heavenly bodies, and an earth;
and, on the earth, water, air, fire, minerals, and several other
such things which are the most common and the simplest of
all, and hence the easiest to know. Then, when I wanted to
proceed to more particular things, so many different ones pre-
sented themselves to me that I did not believe it possible for
the human mind to distinguish the Forms or Species* of bodies
that are on the earth from a host of others which might be
there, if it had been the will of God to put them there. Con-
sequently, I did not think there was any other way to make
them useful to us, than by progressing from effects to causes
and by engaging in many individual observations. Following
which, I cast my mind over all the objects that had ever pre-
sented themselves to my senses, and I venture to declare that I
have not noticed anything which I could not explain quite
easily by the principles I had found. But I must also acknow-
ledge that the power of nature is so ample and vast, and these
principles so simple and general, that I am able to observe
hardly any particular effect without knowing from the begin-
ning that it can be deduced from the principles in many differ-
ent ways, and that my greatest difficulty is normally to find in
which of these ways the effect depends on them. For I know o
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