On Aristotle's "Categories 9-15"

"Aristotle classified the things in the world into ten categories: substance, quantity, quality, relation, etcetera. Plotinus, the founder of Neoplatonism, attacked the classification, accepting only the first four categories, rejecting the other six, and adding one of his own: change. He preferred Plato's classification into five kinds, including change. In this part of his commentary, Simplicius records the controversy on the six categories rejected by Plotinus: acting, being acted upon, being in a position, when, where, and having on. Plotinus' pupil and editor, Porphyry, defended all six categories as applicable to the physical world, even if not to the world of Platonic Forms to which Platonist studies must eventually progress. Porphyry's pupil, Iamblichus, went further: taken in a suitable sense, Aristotle's categories apply also to the world of Forms, although they require Pythagorean reinterpretation. Simplicius may be closer to Porphyry than to Iamblichus, and indeed Porphyry's defense established Aristotle's categories once and for all in Western thought. But the controversy of this period nonetheless revealed more effectively than any modern discussion the profound difficulties in Aristotle's categorial scheme."--BOOK JACKET.