On Generation and corruption
than one. Indeed, even the plants, though it might be thought they are
fed by one substance only, viz. by Water, are fed by more than one:
for Earth has been mixed with the Water. That is why farmers too
endeavour to mix before watering. Although food is akin to the matter,
that which is fed is the 'figure'-i.e. the 'form' taken along with the
matter. This fact enables us to understand why, whereas all the
'simple' bodies come-to-be out of one another, Fire is the only one of
them which (as our predecessors also assert) 'is fed'. For Fire
alone-or more than all the rest-is akin to the 'form' because it tends
by nature to be borne towards the limit. Now each of them naturally
tends to be borne towards its own place; but the 'figure'-i.e. the
'form'-Of them all is at the limits.
Thus we have explained that all the compound bodies are composed
of all the 'simple' bodies.
Since some things are such as to come-to-be and pass-away, and since
coming-to-be in fact occurs in the region about the centre, we must
explain the number and the nature of the 'originative sources' of
all coming-to-be alike: for a grasp of the true theory of any
universal facilitates the understanding of its specific forms.
The 'originative sources', then, of the things which come-to-be
are equal in number to, and identical in kind with, those in the
sphere of the eternal and primary things. For there is one in the
sense of 'matter', and a second in the sense of 'form': and, in
addition, the third 'originative source' must be present as well.
For the two first are not sufficient to bring things into being, any
more than they are adequate to account for the primary things.
Now cause, in the sense of material origin, for the things which
are such as to come-to-be is 'that which can be-and-not-be': and
this is identical with'that which can come-to-be-and-pass-away', since