The Complete Aristotle (eng.)

it
enters the heaven itself, which as it were inhales it, from the
infinite air. Further it is the void which distinguishes the
natures of things, as if it were like what separates and
distinguishes the terms of a series. This holds primarily in the
numbers, for the void distinguishes their nature.
    These, then, and so many, are the main grounds on which people
have argued for and against the existence of the void.
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7
    As a step towards settling which view is true, we must determine
the meaning of the name.
    The void is thought to be place with nothing in it. The reason
for this is that people take what exists to be body, and hold that
while every body is in place, void is place in which there is no
body, so that where there is no body, there must be void.
    Every body, again, they suppose to be tangible; and of this
nature is whatever has weight or lightness.
    Hence, by a syllogism, what has nothing heavy or light in it, is
void.
    This result, then, as I have said, is reached by syllogism. It
would be absurd to suppose that the point is void; for the void
must be place which has in it an interval in tangible body.
    But at all events we observe then that in one way the void is
described as what is not full of body perceptible to touch; and
what has heaviness and lightness is perceptible to touch. So we
would raise the question: what would they say of an interval that
has colour or sound-is it void or not? Clearly they would reply
that if it could receive what is tangible it was void, and if not,
not.
    In another way void is that in which there is no ‘this’ or
corporeal substance. So some say that the void is the matter of the
body (they identify the place, too, with this), and in this they
speak incorrectly; for the matter is not separable from the things,
but they are inquiring about the void as about something
separable.
    Since we have determined the nature of place, and void must, if
it exists, be place deprived of body, and we have stated both in
what sense place exists and in what sense it does not, it is plain
that on this showing void does not exist, either unseparated or
separated; the void is meant to be, not body but rather an interval
in body. This is why the void is thought to be something, viz.
because place is, and for the same reasons. For the fact of motion
in respect of place comes to the aid both of those who maintain
that place is something over and above the bodies that come to
occupy it, and of those who maintain that the void is something.
They state that the void is the condition of movement in the sense
of that in which movement takes place; and this would be the kind
of thing that some say place is.
    But there is no necessity for there being a void if there is
movement. It is not in the least needed as a condition of movement
in general, for a reason which, incidentally, escaped Melissus;
viz. that the full can suffer qualitative change.
    But not even movement in respect of place involves a void; for
bodies may simultaneously make room for one another, though there
is no interval separate and apart from the bodies that are in
movement. And this is plain even in the rotation of continuous
things, as in that of liquids.
    And things can also be compressed not into a void but because
they squeeze out what is contained in them (as, for instance, when
water is compressed the air within it is squeezed out); and things
can increase in size not only by the entrance of something but also
by qualitative change; e.g. if water were to be transformed into
air.
    In general, both the argument about increase of size and that
about water poured on to the ashes get in their own way. For either
not any and every part of the body is increased, or bodies may be
increased otherwise than by the addition of body, or there may be
two bodies in the same place (in which case they are claiming to
solve a quite general difficulty, but are not proving the existence
of void), or the whole body must be void, if it is increased in
every part and is increased by means of void. The same argument
applies to the ashes.
    It is evident, then, that it is easy to refute the arguments by
which they prove the existence of the void.
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8
    Let us explain again that there is no void existing separately,
as some maintain. If each of the simple bodies has a natural
locomotion, e.g. fire upward and earth downward and towards the
middle of the