Until the launch of this series nearly twenty years ago, the 15,000 volumes of the ancient Greek commentators on Aristotle, written mainly between 200 and 600 AD, constituted the largest corpus of extant Greek philosophical writings not translated into English or other European languages. Over 40 volumes have now appeared in the series, which is planned in some 80 volumes altogether. Syrianus, originally from Alexandria, moved to Athens and became the head of the Academy there after the death of Plutarch of Athens. Syrianus attacked Aristotle in his commentary on Books 13 and 14 of the "Metaphysics", just as his pupil Proclus was to do later in his commentaries on Plato. This is because in "Metaphysics 13-14", Aristotle himself was being thoroughly polemical towards Platonism, in particular against the Academic doctrine of Form-numbers and the whole concept of separable number. In reply, Syrianus gives an account of mathematical number and of geometrical entities, and of how all of these are processed in the mind, which was to influence Proclus and all subsequent Neoplatonists.