  Philoponus’ battle against eternalism may be divided into three stages. The treatise Against Proclus is followed by a second and even more provocative publication, On the Eternity of the World against Aristotle. This work was published c. 530–534 and involved a close scrutiny of the first chapters of Aristotle’s On the Heavens (his theory of ether as the fifth element, of which the heavenly bodies are made) and the eighth book of the Physics (arguing for the eternity of time and motion). The third stage is represented by one, perhaps two, non-polemical treatises that have survived in fragments which indicate that numerous arguments against eternity and for creation were arranged in some kind of systematic order.