Aristotle's "De Caelo" III: introduction, translation and commentary

<P>This is the first full-scale commentary on Aristotle's <I>de Caelo</I> III to appear in recent decades. <I>de Caelo</I> III can serve as a good introduction to Aristotle's physics and its character. In it he answers some very general questions about the elements of all material things except celestial objects: how many these elements are, why they cannot be infinitely many but must be more than one, whether they are eternal or can be generated and decay, and, if the second, how. His discussion is often framed as a critique of rival theories, and he argues systematically against the geometri