Encapsulating Aristotle’s discussions of change in Physics i 7 and 8, and putting the matter more crisply than he himself does, we have the following simple argument for matter and form: (1) a necessary condition of there being change is the existence of matter and form; (2) there is change; hence (3) there are matter and form. The second premise is a phainomenon; so, if that is accepted without further defense, only the first requires justification. The first premise is justified by the thought