This paper argues that Augustine did not take the proof inSoliloquia2.22-4, which centers on the Aristotelian notion of ‘being in a subject’, from a single source but constructed it in a deliberately imperfect manner from several passages from Porphyry’s works on Aristotle’sCategoriesin order to supplement it with further arguments in Book Three. InDe immortalitate animaeAugustine explicitly discloses the weaknesses of the proof and repairs them by means of a Neoplatonic notion of causality.

_ Source: _Volume 11, Issue 1, pp 26 - 45 In his _Commentary on the Timaeus_, Porphyry of Tyre argued against the second-century Platonist Atticus’ thesis that the creation in Plato’s _Timaeus_ was a process from a point of time. This paper focuses on the summary of one of Porphyry’s arguments against this thesis exposed in Book 2 of Proclus’ _Commentary on the Timaeus_. It argues that Proclus does justice to Porphyry’s views and that the argument points to a classification (...) of powers in Porphyry’s metaphysics that has so far been neglected by scholars. (shrink)