 Though the dedication to the emperors tells us that Alexander was appointed to a chair in philosophy, there is not sufficient evidence as to whether, as is often asserted, he obtained one of the four chairs, representing the four traditional schools, established in Athens by Marcus Aurelius in 176 CE. There were similar established chairs in several cities (on Athens see Lynch 1972, 192–207; 213–216). Given the amount and scope of his writing he must have been an active teacher with a flourishing school. It is therefore possible that some of the short essays attributed to Alexander are actually the production of one of his collaborators or disciples. But nothing is known about any of his associates and students (cf. Sharples 1990a). To us his work therefore represents both the heyday and the end of the series of commentators who explained Aristotle exclusively on the basis of Aristotelian texts, without commitment to some other doctrine. Alexander concludes the series of these purely ‘Peripatetic’ commentators (beginning with Andronicus of Rhodes in the first century BCE), who try to explain “Aristotle by Aristotle” (Moraux 1942, xvi). Though later commentators, starting with Porphyry, the disciple and editor of Plotinus, relied heavily on his works, they had a Neo-Platonist approach. Since Porphyry lived considerably later than Alexander (ca. 234–305/10 CE), Alexander’s school may have continued to exist until it became outmoded by the ‘Neo-Platonist turn’. Porphyry’s report that Plotinus included texts by Alexander ‘and related authors in his discussions’ (The Life of Plotinus, 14.13) makes this quite likely. Alexander’s commentaries formed a central part of the Arabic tradition and was heavily used by Maimonides. It thereby influenced the Latin West after the revival of Aristotelianism in the Middle Ages. The scarcity of Latin translations of Alexander’s commentaries suggests a certain preference for the interpretation of the later, Neoplatonist, commentators. If William of Moerbeke confined his translations of Alexander’s commentaries to those on the Meteorologica and the De sensu that may in part be due to the availability of Boethius’ commentaries on Aristotle’s Prior Analytics and the Topics, but it leaves unexplained why he did not translate the commentary on the Metaphysics. 