It says here* that in book twelve of his Metaphysics, “…Aristotle sets out to prove the existence of an eternal unchanging First Cause of the eternal circular movement of the heavenly sphere and the world of change. … [He argues that] the First Cause does not directly bring about the change but acts as the end of the activities of the spheres of the fixed stars, as an object of love and desire. The spheres, according to Aristotle, are intelligent beings, and the unchanging motion of the first sphere is motivated by its desire to emulate the fixed existence of the First Cause. Its eternal circular motion is the closest approximation of the heavenly spheres to the perfection of the First Cause.”
So if I understand this correctly, Aristotle is saying that in its relentless pursuit of perfection, the first sphere goes in circles—chasing its own tail as it were—and never really gets anywhere. Hm. Maybe he’s on to something!
*Ari Ackerman, “Miricles,” in Nadler, Steven and T.M. Rudavsky (eds.), The Cambridge History of Jewish Philosophy, Cambridge University Press, New York, 2009, pages 366–367.