Book 8
5
Now these are the sensible substances, and all sensible substances contain matter.
6
And the substrate is substance; in one sense matter (by matter I mean that which is not actually, but is potentially, an individual thing); and in another the formula and the specific shape (which is an individual thing and is theoretically separable); and thirdly there is the combination of the two, which alone admits of generation and destruction,Cf. Aristot. Met. 7.8. and is separable in an unqualified sense—for of substances in the sense of formula some are separableIn point of fact the only form which is absolutely separable is Mind or Reason. Cf. Aristot. Met. 12.7, 9. and some are not.
7
That matter is also substance is evident; for in all opposite processes of change there is something that underlies those processes; e.g., if the change is of place , that which is now in one place and subsequently in another; and if the change is of magnitude , that which is now of such-and-such a size, and subsequently smaller or greater; and if the change is of quality , that which is now healthy and subsequently diseased.
