In his polemical treatise against Aristotle preserved in part by Eusebius, the second century Platonist Atticus argues in defense of Plato‘s view of the eternity of the universe that the universe, insofar as it is bodily, is perishable by nature, but nonetheless is imperishable by the will of God (fr. 4 des Places). And this power of God to render what is naturally perishable imperishable is, according to Atticus, testament to the breadth and depth of his providence. My intent in this paper is to examine various responses to Atticus’ argument during the period of Middle Platonism and later among the Neoplatonists to determine the tradition of commentary on this matter. After setting the background to the debate by looking at various passages in Plato and at Aristotle’s reaction to Plato in De caelo, I plan to cover briefly the views of representatives of both eras of later Platonism, including Plutarch, Calvenus Taurus, Alcinous, Apuleius, the anonymous philosopher discussed by Diogenes Laertius (III, 71), and Plotinus (with regard to whether they support or oppose Atticus), but will focus on two well-known and important repudiations of the position taken by Atticus, one from the Peripatetic Alexander of Aphrodisias (Quaest. 1. 18), who may not have targeted Atticus directly, and the other from the Neoplatonist Proclus (In Tim. 3. 212, 7ff.), who does take on Atticus, as well as Plutarch and Severus, by name. Alexander’s position, briefly stated, is that if the universe is by nature perishable, it is absolutely impossible that it be otherwise; and not even God can bring to pass what is absolutely impossible. Proclus’ rejection of Atticus’ argument is, in effect at least, a rejection of Alexander’s as well. He begins his response with a point that seems to address both his named Middle Platonists and the Peripatetics: if the universe is perishable by nature, then we are left with the untenable conclusion that God must be responsible for its perishability (and so, for the Peripatetics, for its actual dissolution according their understanding of Plato), since as creator he is responsible for its nature. As for Atticus, Plutarch, and Severus, he contends—through an interpretation of Atticus that may well misrepresent his argument— that it is absurd to argue that the universe is by nature perishable but imperishable solely by the will of God. For Proclus, God’s will and power cannot in this or any other way function separately, so that his will somehow makes up for what he lacks in power. As creator, the Demiurge embraces within himself the final, paradigmatic, and efficient causes of the universe, and so if it is his will that the universe be imperishable, a fortiori hehas the causal power to make it so by its nature. I will show that this is no ad hoc argument, but is rooted in a fundamental principle of Proclan metaphysics that in the case of all higher causes, their power to create by their essences extends more widely than their creation by deliberate choice (E. T. Prop. 57). Yet, as we shall see, Proclus’ Demiurge does not possess the absolute power of Atticus’ Demiurge to override Necessity, for, in Proclus’ opinion, the imperishability of the universe is qualified and limited. This qualification appears to leave some room for the operation of divine will in determining the eternity of the universe, but in a manner that would have been thoroughly objectionable to Atticus.