On Generation and Corruption

by Aristotle

Written circa 350 B.C.
Translated by H. H. Joachim

Book I.8


Now we have discussed 'indivisible planes' in the preceding
treatise.' But with regard to the assumption of 'indivisible
solids', although we must not now enter upon a detailed study of its
consequences, the following criticisms fall within the compass of a
short digression: i. The Atomists are committed to the view that every
'indivisible' is incapable alike of receiving a sensible property (for
nothing can 'suffer action' except through the void) and of
producing one-no 'indivisible' can be, e.g. either hard or cold. Yet
it is surely a paradox that an exception is made of 'the hot'-'the
hot' being assigned as peculiar to the spherical figure: for, that
being so, its 'contrary' also ('the cold') is bound to belong to
another of the figures. If, however, these properties (heat and
cold) do belong to the 'indivisibles', it is a further paradox that
they should not possess heaviness and lightness, and hardness and
softness. And yet Democritus says 'the more any indivisible exceeds,
the heavier it is'-to which we must clearly add 'and the hotter it
is'. But if that is their character, it is impossible they should
not be affected by one another: the 'slightly-hot indivisible', e.g.
will inevitably suffer action from one which far exceeds it in heat.
Again, if any 'indivisible' is 'hard', there must also be one which is
'soft': but 'the soft' derives its very name from the fact that it
suffers a certain action-for 'soft' is that which yields to pressure.

II. But further, not only is it paradoxical (i) that no property
except figure should belong to the 'indivisibles': it is also
paradoxical (ii) that, if other properties do belong to them, one only
of these additional properties should attach to each-e.g. that this
'indivisible' should be cold and that 'indivisible' hot. For, on
that supposition, their substance would not even be uniform. And it is
equally impossible (iii) that more than one of these additional
properties should belong to the single 'indivisible'. For, being
indivisible, it will possess these properties in the same point-so
that, if it 'suffers action' by being chilled, it will also, qua
chilled, 'act' or 'suffer action' in some other way. And the same line
of argument applies to all the other properties too: for the
difficulty we have just raised confronts, as a necessary
consequence, all who advocate 'indivisibles' (whether solids or
planes), since their 'indivisibles' cannot become either 'rarer' or
'derser' inasmuch as there is no void in them.

III. It is a further paradox that there should be small
'indivisibles', but not large ones. For it is natural enough, from the
ordinary point of view, that the larger bodies should be more liable
to fracture than the small ones, since they (viz. the large bodies)
are easily broken up because they collide with many other bodies.
But why should indivisibility as such be the property of small, rather
than of large, bodies?

IV. Again, is the substance of all those solids uniform, or do
they fall into sets which differ from one another-as if, e.g. some
of them, in their aggregated bulk, were 'fiery', others earthy'? For
(i) if all of them are uniform in substance, what is it that separated
one from another? Or why, when they come into contact, do they not
coalesce into one, as drops of water run together when drop touches
drop (for the two cases are precisely parallel)? On the other hand
(ii) if they fall into differing sets, how are these characterized? It
is clear, too, that these, rather than the 'figures', ought to be
postulated as 'original reals', i.e. causes from which the phenomena
result. Moreover, if they differed in substance, they would both act
and suffer action on coming into reciprocal contact.

V. Again, what is it which sets them moving? For if their 'mover' is
other than themselves, they are such as to 'suffer action'. If, on the
other hand, each of them sets itself in motion, either (a) it will
be divisible ('imparting motion' qua this, 'being moved' qua that), or
(b) contrary properties will attach to it in the same respect-i.e.
'matter' will be identical in-potentiality as well as
numerically-identical.