 In Physics, 3.1, Aristotle defines motion (Gk. kinēsis, Ar. ḥaraka) as the entelecheia of potential as potential. Aristotle himself apparently coined the term entelecheia, which might mean either “actualization,” as in a process, or “actuality,” as in the completion of a process. Given the ambiguity of this term, it was a matter of some concern among later Greek commentators to understand Aristotle’s precise meaning. The details of the Greek debate need not concern us unduly, since the issue for philosophers in the medieval Islamic world was all but settled by the choice of the Arabic translator of Aristotle’s Physics, who rendered entelecheia as “perfection” or “completion” (kamāl). Consequently, for philosophers such as Avicenna, motion was understood as a sort of actuality or perfection, as opposed to an actualization or a process. 