Dexippus, a pupil or follower of lamblichus, preserves a crucial moment in the Neoplatonist interpretation of Aristotle. Aristotle's Categories has been attacked by Plotinus, but Porphyry's defence proved decisive, so that the Categories was acceptable as compatible with Platonism and an essential introduction to the Neoplatonist curriculum. Porphyry's main commentary on the Categories, however, containing the vital defence, is lost, as is that of his pupil lamblichus. The ideas of these two principal Neoplatonists can be reconstructed, in part, from Dexippus.