ArcaMax Publishing > Books > Philosophy > Selections from the Principles of Philosophy > Section 7
Selections from the Principles of Philosophy

Rene Descartes

XIV. Wherein place and space differ.

The terms place and space, however, differ in signification, because
place more expressly designates situation than magnitude or figure,
while, on the other hand, we think of the latter when we speak of
space. For we frequently say that a thing succeeds to the place of
another, although it be not exactly of the same magnitude or figure;
but we do not therefore admit that it occupies the same space as the
other; and when the situation is changed we say that the place also
is changed, although there are the same magnitude and figure as
before: so that when we say that a thing is in a particular place,
we mean merely that it is situated in a determinate way in respect
of certain other objects; and when we add that it occupies such a
space or place, we understand besides that it is of such determinate
magnitude and figure as exactly to fill this space.

 XV. How external place is rightly taken for the superficies of the
surrounding body.

And thus we never indeed distinguish space from extension in length,
breadth, and depth; we sometimes, however, consider place as in the
thing placed, and at other times as out of it. Internal place indeed
differs in no way from space; but external place may be taken for
the superficies that immediately surrounds the thing placed. It
ought to be remarked that by superficies we do not here understand
any part of the surrounding body, but only the boundary between the
surrounding and surrounded bodies, which is nothing more than a
mode; or at least that we speak of superficies in general which is
no part of one body rather than another, but is always considered
the same, provided it retain the same magnitude and figure. For
although the whole surrounding body with its superficies were
changed, it would not be supposed that the body which was surrounded
by it had therefore changed its place, if it meanwhile preserved the
same situation with respect to the other bodies that are regarded as
immovable. Thus, if we suppose that a boat is carried in one
direction by the current of a stream, and impelled by the wind in
the opposite with an equal force, so that its situation with respect
to the banks is not changed, we will readily admit that it remains
in the same place, although the whole superficies which surrounds it
is incessantly changing.

 XVI. That a vacuum or space in which there is absolutely no body is
repugnant to reason.

With regard to a vacuum, in the philosophical sense of the term,
that is, a space in which there is no substance, it is evident that
such does not exist, seeing the extension of space or internal place
is not different from that of body. For since from this alone, that
a body has extension in length, breadth, and depth, we have reason
to conclude that it is a substance, it being absolutely
contradictory that nothing should possess extension, we ought to
form a similar inference regarding the space which is supposed void,
viz., that since there is extension in it there is necessarily also
substance.

 XVII. That a vacuum in the ordinary use of the term does not
exclude all body.

And, in truth, by the term vacuum in its common use, we do not mean
a place or space in which there is absolutely nothing, but only a
place in which there is none of those things we presume ought to be
there. Thus, because a pitcher is made to hold water, it is said to
be empty when it is merely filled with air; or if there are no fish
in a fish-pond, we say there is nothing in it, although it be full
of water; thus a vessel is said to be empty, when, in place of the
merchandise which it was designed to carry, it is loaded with sand
only, to enable it to resist the violence of the wind; and, finally,
it is in the same sense that we say space is void when it contains
nothing sensible, although it contain created and self-subsisting
matter; for we are not in the habit of considering the bodies near
us, unless in so far as they cause in our organs of sense,
impressions strong enough to enable us to perceive them. And if, in
place of keeping in mind what ought to be understood by these terms
a vacuum and nothing, we afterwards suppose that in the space we
called a vacuum, there is not only no sensible object, but no object
at all, we will fall into the same error as if, because a pitcher in
which there is nothing but air, is, in common speech, said to be
empty, we were therefore to judge that the air contained in it is
not a substance (RES SUBSISTENS).

 XVIII. How the prejudice of an absolute vacuum is to be corrected.

We have almost all fallen into this error from the earliest age,
for, observing that there is no necessary connection between a
vessel and the body it contains, we thought that God at least could
take from a vessel the body which occupied it, without it being
necessary that any other should be put in the place of the one
removed. But that we may be able now to correct this false opinion,
it is necessary to remark that there is in truth no connection
between the vessel and the particular body which it contains, but
that there is an absolutely necessary connection between the concave
figure of the vessel and the extension considered generally which
must be comprised in this cavity; so that it is not more
contradictory to conceive a mountain without a valley than such a
cavity without the extension it contains, or this extension apart
from an extended substance, for, as we have often said, of nothing
there can be no extension. And accordingly, if it be asked what
would happen were God to remove from a vessel all the body contained
in it, without permitting another body to occupy its place, the
answer must be that the sides of the vessel would thus come into
proximity with each other. For two bodies must touch each other when
there is nothing between them, and it is manifestly contradictory
for two bodies to be apart, in other words, that there should be a
distance between them, and this distance yet be nothing; for all
distance is a mode of extension, and cannot therefore exist without
an extended substance.

 XIX. That this confirms what was said of rarefaction.

After we have thus remarked that the nature of corporeal substance
consists only in its being an extended thing, and that its extension
is not different from that which we attribute to space, however
empty, it is easy to discover the impossibility of any one of its
parts in any way whatsoever occupying more space at one time than at
another, and thus of being otherwise rarefied than in the way
explained above; and it is easy to perceive also that there cannot
be more matter or body in a vessel when it is filled with lead or
gold, or any other body however heavy and hard, than when it but
contains air and is supposed to be empty: for the quantity of the
parts of which a body is composed does not depend on their weight or
hardness, but only on the extension, which is always equal in the
same vase.

 XX. That from this the non-existence of atoms may likewise be
demonstrated.

We likewise discover that there cannot exist any atoms or parts of
matter that are of their own nature indivisible. For however small
we suppose these parts to be, yet because they are necessarily
extended, we are always able in thought to divide any one of them
into two or more smaller parts, and may accordingly admit their
divisibility. For there is nothing we can divide in thought which we
do not thereby recognize to be divisible; and, therefore, were we to
judge it indivisible our judgment would not be in harmony with the
knowledge we have of the thing; and although we should even suppose
that God had reduced any particle of matter to a smallness so
extreme that it did not admit of being further divided, it would
nevertheless be improperly styled indivisible, for though God had
rendered the particle so small that it was not in the power of any
creature to divide it, he could not however deprive himself of the
ability to do so, since it is absolutely impossible for him to
lessen his own omnipotence, as was before observed. Wherefore,
absolutely speaking, the smallest extended particle is always
divisible, since it is such of its very nature.

 XXI. It is thus also demonstrated that the extension of the world
is indefinite.

We further discover that this world or the whole (universitas) of
corporeal substance, is extended without limit, for wherever we fix
a limit, we still not only imagine beyond it spaces indefinitely
extended, but perceive these to be truly imaginable, in other words,
to be in reality such as we imagine them; so that they contain in
them corporeal substance indefinitely extended, for, as has been
already shown at length, the idea of extension which we conceive in
any space whatever is plainly identical with the idea of corporeal
substance.

 XXII. It also follows that the matter of the heavens and earth is
the same, and that there cannot be a plurality of worlds.

And it may also be easily inferred from all this that the earth and
heavens are made of the same matter; and that even although there
were an infinity of worlds, they would all be composed of this
matter; from which it follows that a plurality of worlds is
impossible, because we clearly conceive that the matter whose nature
consists only in its being an extended substance, already wholly
occupies all the imaginable spaces where these other worlds could
alone be, and we cannot find in ourselves the idea of any other
matter.

 XXIII. That all the variety of matter, or the diversity of its
forms, depends on motion.

There is therefore but one kind of matter in the whole universe, and
this we know only by its being extended. All the properties we
distinctly perceive to belong to it are reducible to its capacity of
being divided and moved according to its parts; and accordingly it
is capable of all those affections which we perceive can arise from
the motion of its parts. For the partition of matter in thought
makes no change in it; but all variation of it, or diversity of
form, depends on motion. The philosophers even seem universally to
have observed this, for they said that nature was the principle of
motion and rest, and by nature they understood that by which all
corporeal things become such as they are found in experience.

 XXIV. What motion is, taking the term in its common use.

But motion (viz., local, for I can conceive no other kind of motion,
and therefore I do not think we ought to suppose there is any other
in nature), in the ordinary sense of the term, is nothing more than
the action by which a body passes from one place to another. And
just as we have remarked above that the same thing may be said to
change and not to change place at the same time, so also we may say
that the same thing is at the same time moved and not moved. Thus,
for example, a person seated in a vessel which is setting sail,
thinks he is in motion if he look to the shore that he has left, and
consider it as fixed; but not if he regard the ship itself, among
the parts of which he preserves always the same situation. Moreover,
because we are accustomed to suppose that there is no motion without
action, and that in rest there is the cessation of action, the
person thus seated is more properly said to be at rest than in
motion, seeing he is not conscious of being in action.

 XXV. What motion is properly so called.

But if, instead of occupying ourselves with that which has no
foundation, unless in ordinary usage, we desire to know what ought
to be understood by motion according to the truth of the thing, we
may say, in order to give it a determinate nature, that it is THE
TRANSPORTING OF ONE PART OF MATTER OR OF ONE BODY FROM THE VICINITY
OF THOSE BODIES THAT ARE IN IMMEDIATE CONTACT WITH IT, OR WHICH WE
REGARD AS AT REST, to the vicinity of other bodies. By a body as a
part of matter, I understand all that which is transferred together,
although it be perhaps composed of several parts, which in
themselves have other motions; and I say that it is the transporting
and not the force or action which transports, with the view of
showing that motion is always in the movable thing, not in that
which moves; for it seems to me that we are not accustomed to
distinguish these two things with sufficient accuracy. Farther, I
understand that it is a mode of the movable thing, and not a
substance, just as figure is a property of the thing figured, and
repose of that which is at rest.



PART III.

OF THE VISIBLE WORLD.

 I. That we cannot think too highly of the works of God.

Having now ascertained certain principles of material things, which
were sought, not by the prejudices of the senses, but by the light
of reason, and which thus possess so great evidence that we cannot
doubt of their truth, it remains for us to consider whether from
these alone we can deduce the explication of all the phenomena of
nature. We will commence with those phenomena that are of the
greatest generality, and upon which the others depend, as, for
example, with the general structure of this whole visible world. But
in order to our philosophizing aright regarding this, two things are
first of all to be observed. The first is, that we should ever bear
in mind the infinity of the power and goodness of God, that we may
not fear falling into error by imagining his works to be too great,
beautiful, and perfect, but that we may, on the contrary, take care
lest, by supposing limits to them of which we have no certain
knowledge, we appear to think less highly than we ought of the power
of God.

 II. That we ought to beware lest, in our presumption, we imagine
that the ends which God proposed to himself in the creation of the
world are understood by us.

The second is, that we should beware of presuming too highly of
ourselves, as it seems we should do if we supposed certain limits to
the world, without being assured of their existence either by
natural reasons or by divine revelation, as if the power of our
thought extended beyond what God has in reality made; but likewise
still more if we persuaded ourselves that all things were created by
God for us only, or if we merely supposed that we could comprehend
by the power of our intellect the ends which God proposed to himself
in creating the universe.

 III. In what sense it may be said that all things were created for
the sake of man.

For although, as far as regards morals, it may be a pious thought to
believe that God made all things for us, seeing we may thus be
incited to greater gratitude and love toward him; and although it is
even in some sense true, because there is no created thing of which
we cannot make some use, if it be only that of exercising our mind
in considering it, and honouring God on account of it, it is yet by
no means probable that all things were created for us in this way
that God had no other end in their creation; and this supposition
would be plainly ridiculous and inept in physical reasoning, for we
do not doubt but that many things exist, or formerly existed and
have now ceased to be, which were never seen or known by man, and
were never of use to him.



PART IV.

OF THE EARTH.

 CLXXXVIII. Of what is to be borrowed from disquisitions on animals
and man to advance the knowledge of material objects.

I should add nothing farther to this the Fourth Part of the
Principles of Philosophy, did I purpose carrying out my original
design of writing a Fifth and Sixth Part, the one treating of things
possessed of life, that is, animals and plants, and the other of
man. But because I have not yet acquired sufficient knowledge of all
the matters of which I should desire to treat in these two last
parts, and do not know whether I shall ever have sufficient leisure
to finish them, I will here subjoin a few things regarding the
objects of our senses, that I may not, for the sake of the latter,
delay too long the publication of the former parts, or of what may
be desiderated in them, which I might have reserved for explanation
in those others: for I have hitherto described this earth, and
generally the whole visible world, as if it were merely a machine in
which there was nothing at all to consider except the figures and
motions of its parts, whereas our senses present to us many other
things, for example colours, smells, sounds, and the like, of which,
if I did not speak at all, it would be thought I had omitted the
explication of the majority of the objects that are in nature.

 CLXXXIX. What perception (SENSUS) is, and how we perceive.

We must know, therefore, that although the human soul is united to
the whole body, it has, nevertheless, its principal seat in the
brain, where alone it not only understands and imagines, but also
perceives; and this by the medium of the nerves, which are extended
like threads from the brain to all the other members, with which
they are so connected that we can hardly touch any one of them
without moving the extremities of some of the nerves spread over it;
and this motion passes to the other extremities of those nerves
which are collected in the brain round the seat of the soul,
[Footnote: *** FOOTNOTE NOT VISIBLE IN PAGE IMAGE (#98, Text p 195)]
as I have already explained with sufficient minuteness in the fourth
chapter of the Dioptrics. But the movements which are thus excited
in the brain by the nerves variously affect the soul or mind, which
is intimately conjoined with the brain, according to the diversity
of the motions themselves. And the diverse affections of the mind or
thoughts that immediately arise from these motions, are called
perceptions of the senses (SENSUUM PERCEPTIONES), or, as we commonly
speak, sensations (SENSUS).

 CXC. Of the distinction of the senses; and, first, of the internal,
that is, of the affections of the mind (passions), and the natural
appetites.

The varieties of these sensations depend, firstly, on the diversity
of the nerves themselves, and, secondly, of the movements that are
made in each nerve. We have not, however, as many different senses
as there are nerves. We can distinguish but seven principal classes
of nerves, of which two belong to the internal, and the other five
to the external senses. The nerves which extend to the stomach, the
oesophagus, the fauces, and the other internal parts that are
subservient to our natural wants, constitute one of our internal
senses. This is called the natural appetite (APPETITUS NATURALIS).
The other internal sense, which embraces all the emotions
(COMMOTIONES) of the mind or passions, and affections, as joy,
sadness, love, hate, and the like, depends upon the nerves which
extend to the heart and the parts about the heart, and are
exceedingly small; for, by way of example, when the blood happens to
be pure and well tempered, so that it dilates in the heart more
readily and strongly than usual, this so enlarges and moves the
small nerves scattered around the orifices, that there is thence a
corresponding movement in the brain, which affects the mind with a
certain natural feeling of joy; and as often as these same nerves
are moved in the same way, although this is by other causes, they
excite in our mind the same feeling (sensus, sentiment). Thus, the
imagination of the enjoyment of a good does not contain in itself
the feeling of joy, but it causes the animal spirits to pass from
the brain to the muscles in which these nerves are inserted; and
thus dilating the orifices of the heart, it also causes these small
nerves to move in the way appointed by nature to afford the
sensation of joy. Thus, when we receive news, the mind first of all
judges of it, and if the news be good, it rejoices with that
intellectual joy (GAUDIUM INTELLECTUALE) which is independent of any
emotion (COMMOTIO) of the body, and which the Stoics did not deny to
their wise man [although they supposed him exempt from all passion].
But as soon as this joy passes from the understanding to the
imagination, the spirits flow from the brain to the muscles that are
about the heart, and there excite the motion of the small nerves, by
means of which another motion is caused in the brain, which affects
the mind with the sensation of animal joy (LAETITIA ANIMALIS). On
the same principle, when the blood is so thick that it flows but
sparingly into the ventricles of the heart, and is not there
sufficiently dilated, it excites in the same nerves a motion quite
different from the preceding, which, communicated to the brain,
gives to the mind the sensation of sadness, although the mind itself
is perhaps ignorant of the cause of its sadness. And all the other
causes which move these nerves in the same way may also give to the
mind the same sensation. But the other movements of the same nerves
produce other effects, as the feelings of love, hate, fear, anger,
etc., as far as they are merely affections or passions of the mind;
in other words, as far as they are confused thoughts which the mind
has not from itself alone, but from its being closely joined to the
body, from which it receives impressions; for there is the widest
difference between these passions and the distinct thoughts which we
have of what ought to be loved, or chosen, or shunned, etc.,
[although these are often enough found together]. The natural
appetites, as hunger, thirst, and the others, are likewise
sensations excited in the mind by means of the nerves of the
stomach, fauces, and other parts, and are entirely different from
the will which we have to eat, drink, [and to do all that which we
think proper for the conservation of our body]; but, because this
will or appetition almost always accompanies them, they are
therefore named appetites.
Prev Next All
Printer Friendly Version | Send this page to a friend | Discuss this Book
Your email address is safe with us. View our Privacy policy.

The Complete Plays of Gilbert and Sullivan W.S. Gilbert Category: Plays Sections: 50 What's this? Table of Contents		Fiction Non Fiction Short Stories Poetry Plays Sci Fi Religion Biography