Aristotle on the Nature and Motion of the Celestial Sphere: I. The Heavens as Corporeal Substance
In De caelo I–II, Aristotle replaces the Platonic world soul with a self-moving, internally animate “first body”. The article reconstructs Aristotle’s progressive introduction of this not only geometrically, but also physically perfect body, with a special focus on its internal animation. The latter follows from the same principles of animate motion that we encounter the biological treatises, yet Aristotle denies that the first body or simply the celestial sphere has a soul of the kind that he introduces in De anima. The article takes a closer look at various conceptual implications of this denial, including the need to reconcile the insistence on the corporeal nature of the heavens with the premise of its self-sustaining perfection. It is to this end, the article concludes after a detailed examination of several passages including De caelo II,3,286a8–12, that Aristotle recurs to his general notion of god as eternal, changeless and animate actuality: clearly, nothing prevents Aristotle for applying this notion of god to a geometrically and physically perfect substance, although this move raises the question (developed in this article’s forthcoming second part) of how to reconcile this fully natural perfection with the notion of the incorporeal prime mover, a notion apparently sidelined in De caelo itself.