Abstract

It has been discussed whether in his two definitions of nature in Physics II, 1 Aristotle means a mover, a passive principle or both kinds of principles. I argue that he means a mover. I discuss several occurrences of the expression archê kinêseôs in particular in Aristotle's Metaphysics IX and Physics. Aristotle means most often a mover, sometimes »the time/site of the beginning of the motion« and never a passive principle. Finally, I briefly discuss the status and function of the two definitions of nature within the context of Physics II and the entire Physics.