On Generation and corruption
coming-to-be and passing-away, and explained under what conditions
they are predicable, of what subject, and owing to what cause.
Similarly, we have also discussed 'alteration', and explained what
'altering' is and how it differs from coming-to-be and passing-away.
But we have still to investigate the so-called 'elements' of bodies.
For the complex substances whose formation and maintenance are due
to natural processes all presuppose the perceptible bodies as the
condition of their coming-to-be and passing-away: but philosophers
disagree in regard to the matter which underlies these perceptible
bodies. Some maintain it is single, supposing it to be, e.g. Air or
Fire, or an 'intermediate' between these two (but still a body with
a separate existence). Others, on the contrary, postulate two or
more materials-ascribing to their 'association' and 'dissociation', or
to their 'alteration', the coming-to-be and passing-away of things.
(Some, for instance, postulate Fire and Earth: some add Air, making
three: and some, like Empedocles, reckon Water as well, thus
Now we may agree that the primary materials, whose change (whether
it be 'association and dissociation' or a process of another kind)
results in coming-to-be and passingaway, are rightly described as
'originative sources, i.e. elements'. But (i) those thinkers are in
error who postulate, beside the bodies we have mentioned, a single
matter-and that corporeal and separable matter. For this 'body' of
theirs cannot possibly exist without a 'perceptible contrariety': this
'Boundless', which some thinkers identify with the 'original real',
must be either light or heavy, either cold or hot. And (ii) what Plato
has written in the Timaeus is not based on any precisely-articulated
conception. For he has not stated clearly whether his
'Omnirecipient" exists in separation from the 'elements'; nor does
he make any use of it. He says, indeed, that it is a substratum
prior to the so-called 'elements'-underlying them, as gold underlies
the things that are fashioned of gold. (And yet this comparison, if