The hylomorphic interpretation of Aristotle's theory of time quite naturally presents a systematic approach by dividing the task into two stages: first, one should investigate the matter of time, and then one may inquire into the form of time. The burden of this section of the book is to get a conceptual grip on the hulê of time, which is kinêsis, motion.

Here there are a number of issues and questions to be addressed. The first is to sort out Aristotle's claim that time is an aspect of motion (kinêseôs ti). Ursula Coope has produced a reconstruction of Aristotle's argument to this conclusion – which figures as the opening move of Physicsiv.11 – that deserves careful examination. While her reconstruction posits Aristotle's use of a methodological principle familiar from other treatises, I do not believe that she has got the argument in iv.11 right. What I take to be the correct reconstruction of the argument lights the way for the hylomorphic interpretation. I develop my reconstruction in section 3.2 below.

Independent of the question how to understand this particular argument is the larger concern that Aristotle's definition of time is patently circular. How is it possible to read “a number of motion with respect to the before and after” in such a way as to render it non-circular, let alone informative?