The Complete Aristotle (eng.)

or
light, is none the less different in essence from all its
attributes, even if it is not separable from them; I mean the
volume of the wooden cube. So that even if it were separated from
everything else and were neither heavy nor light, it will occupy an
equal amount of void, and fill the same place, as the part of place
or of the void equal to itself. How then will the body of the cube
differ from the void or place that is equal to it? And if there can
be two such things, why cannot there be any number coinciding?
    This, then, is one absurd and impossible implication of the
theory. It is also evident that the cube will have this same volume
even if it is displaced, which is an attribute possessed by all
other bodies also. Therefore if this differs in no respect from its
place, why need we assume a place for bodies over and above the
volume of each, if their volume be conceived of as free from
attributes? It contributes nothing to the situation if there is an
equal interval attached to it as well. [Further it ought to be
clear by the study of moving things what sort of thing void is. But
in fact it is found nowhere in the world. For air is something,
though it does not seem to be so-nor, for that matter, would water,
if fishes were made of iron; for the discrimination of the tangible
is by touch.]
    It is clear, then, from these considerations that there is no
separate void.
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9
    There are some who think that the existence of rarity and
density shows that there is a void. If rarity and density do not
exist, they say, neither can things contract and be compressed. But
if this were not to take place, either there would be no movement
at all, or the universe would bulge, as Xuthus said, or air and
water must always change into equal amounts (e.g. if air has been
made out of a cupful of water, at the same time out of an equal
amount of air a cupful of water must have been made), or void must
necessarily exist; for compression and expansion cannot take place
otherwise.
    Now, if they mean by the rare that which has many voids existing
separately, it is plain that if void cannot exist separate any more
than a place can exist with an extension all to itself, neither can
the rare exist in this sense. But if they mean that there is void,
not separately existent, but still present in the rare, this is
less impossible, yet, first, the void turns out not to be a
condition of all movement, but only of movement upwards (for the
rare is light, which is the reason why they say fire is rare);
second, the void turns out to be a condition of movement not as
that in which it takes place, but in that the void carries things
up as skins by being carried up themselves carry up what is
continuous with them. Yet how can void have a local movement or a
place? For thus that into which void moves is till then void of a
void.
    Again, how will they explain, in the case of what is heavy, its
movement downwards? And it is plain that if the rarer and more void
a thing is the quicker it will move upwards, if it were completely
void it would move with a maximum speed! But perhaps even this is
impossible, that it should move at all; the same reason which
showed that in the void all things are incapable of moving shows
that the void cannot move, viz. the fact that the speeds are
incomparable.
    Since we deny that a void exists, but for the rest the problem
has been truly stated, that either there will be no movement, if
there is not to be condensation and rarefaction, or the universe
will bulge, or a transformation of water into air will always be
balanced by an equal transformation of air into water (for it is
clear that the air produced from water is bulkier than the water):
it is necessary therefore, if compression does not exist, either
that the next portion will be pushed outwards and make the
outermost part bulge, or that somewhere else there must be an equal
amount of water produced out of air, so that the entire bulk of the
whole may be equal, or that nothing moves. For when anything is
displaced this will always happen, unless it comes round in a
circle; but locomotion is not always circular, but sometimes in a
straight line.
    These then are the reasons for which they might say that there
is a void; our statement is based on the assumption that there is a
single matter for contraries, hot and cold and the other natural
contrarieties, and that what exists actually is produced from a
potential