Simplicius and Priscian were two of the seven Neoplatonists who left Athens when the Christian Emperor Justinian closed the pagan school there in AD 529. Their commentaries on works on sense perception, one by Aristotle and one by his successor Theophrastus, are translated here in one volume. Both commentaries give a highly Neoplatonized reading to their Aristotelian subjects and give an insight into late Neoplatonist psychology.