Book 8
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.
8
Similarly, if the change is in respect of being , there is something which is now in course of generation, and subsequently in course of destruction, and which is the underlying substrate, now as this individual thing, and subsequently as deprived of its individuality. In this last process of change the others are involved, but in either one or twoi.e., locomotion does not involve substantial change; alteration may or may not involve it (in Aristot. Met. 9.8.17 we find that it does not); increase or decrease does involve it. of the others it is not involved; for it does not necessarily follow that if a thing contains matter that admits of change of place, it also contains matter that is generable and destructible.e.g., the heavenly bodies, though imperishable, can move in space (Aristot. Met. 8.4.7, Aristot. Met. 12.2.4). The difference between absolute and qualified generation has been explained in the Physics.Aristot. Phys. 225a 12-20; cf. Aristot. De Gen. et Corr. 317a 17-31.
