On Generation and corruption
applies to everything else that is produced in accordance with an art.
On the other hand (b) to say that 'matter generates owing to its
movement' would be, no doubt, more scientific than to make such
statements as are made by the thinkers we have been criticizing. For
what 'alters' and transfigures plays a greater part in bringing,
things into being; and we are everywhere accustomed, in the products
of nature and of art alike, to look upon that which can initiate
movement as the producing cause. Nevertheless this second theory is
not right either.
For, to begin with, it is characteristic of matter to suffer action,
i.e. to be moved: but to move, i.e. to act, belongs to a different
'power'. This is obvious both in the things that come-to-be by art and
in those that come to-be by nature. Water does not of itself produce
out of itself an animal: and it is the art, not the wood, that makes a
bed. Nor is this their only error. They make a second mistake in
omitting the more controlling cause: for they eliminate the
essential nature, i.e. the 'form'. And what is more, since they remove
the formal cause, they invest the forces they assign to the 'simple'
bodies-the forces which enable these bodies to bring things into
being-with too instrumental a character. For 'since' (as they say) 'it
is the nature of the hot to dissociate, of the cold to bring together,
and of each remaining contrary either to act or to suffer action',
it is out of such materials and by their agency (so they maintain)
that everything else comes-to-be and passes-away. Yet (a) it is
evident that even Fire is itself moved, i.e. suffers action.
Moreover (b) their procedure is virtually the same as if one were to
treat the saw (and the various instruments of carpentry) as 'the
cause' of the things that come-to-be: for the wood must be divided
if a man saws, must become smooth if he planes, and so on with the
remaining tools. Hence, however true it may be that Fire is active,
i.e. sets things moving, there is a further point they fail to
observe-viz. that Fire is inferior to the tools or instruments in