This article sheds new light on Themistius’ argument in what is philosophically the most original section of his extant work, namely On Aristotle's On the Soul 100.16–109.3: here, Themistius offers a systematic interpretation of Aristotle's ‘agent’ intellect and its ‘potential’ and ‘passive’ counterparts. A solution to two textual difficulties at 101.36–102.2 is proposed, supported by the Arabic translation. This allows us to see that Themistius engages at length with a Platonizing reading of the enigmatic final lines of De anima III.5, where Aristotle explains ‘why we do not remember’. This Platonizing reading can be safely identified with the one developed in a fragmentary text extant only in Arabic under the title Porphyry's treatise On the soul. While Themistius rejects this reading, he turns out to be heavily influenced by the author's interpretation of the ‘agent’, ‘potential’ and ‘passive’ intellect. These findings offer us a new glimpse into Themistius’ philosophical programme: he is searching for an alternative to both the austere Aristotelianism of Alexander of Aphrodisias and the all too Platonizing reading of Aristotle adopted by thinkers such as Porphyry.