On the standard view, Plotinus ’ disciple and editor, Porphyry , rescued Aristotle and made him central to the Western curriculum once and for all, with the Categories as the first work in the curriculum. In the seventeenth century, Jesuits still chose the Categories as the first work to be translated into Chinese, as being the basis of all further thought (Wardy).
This standard account needs a little qualification. First, Steven Strange has pointed out that Porphyry is able to extract some of his defence out of Plotinus’critique . Frans de Haas provides an important illustration. He argues that in 6.1 , Plotinus decides that the Aristotelian categories of substance, quantity and so on do not possess the reality of genera, for the very Aristotelian reason that the various Aristotelian substances (for example) do not fall under a single definition, and cannot do so, given that some are prior to others. This critique of Aristotle follows Aristotelian lines. Moreover, Plotinus concludes that Aristotle’s ten divisions, which receive from Aristotle not a definition, but a non-defining characterisation, should be seen as merely ten kategoriai, and de Haas argues persuasively that kategoriai are merely names for types of thing. This paves the way for Porphyry to say (in Cat. 58,3-6) that Aristotle’s Categories is about words, insofar as they signify things.
But should we infer that Plotinus and Porphyry agree about Aristotle after all? And do they agree not only on the Categories being about words, but also on Aristotle’s not intending to describe the real beings in the intelligible world of Platonic Forms? This has been argued on the basis of Plotinus 6.1  1 (28-30) and Porphyry in Cat. 91,14-27. But Plotinus and Porphyry do not seem to agree. Whereas the passage in Plotinus may even express disgust at Aristotle omitting what are most of all beings (ta malista onta ), that in Porphyry explicitly offers it as a defence of Aristotle that words are applied first and foremost to perceptible entities. Moreover, Dexippus, who is influenced by Porphyry, offers it as an explicit reply to Plotinus that Aristotle’s Categories is addressing beginners, in Cat. 40,14-25. Further, Plotinus does not seem content even with Aristotle’s non-definitional characterisations of his ten categories, and accepts only four of the categories for describing the perceptible world.
Iamblichus offered a quite different defence of Aristotle with his ‘intellective interpretation’: the definitions of the different categories do after all apply, though in a different sense , to the intelligible world. The interpretations of Porphyry and Iamblichus both leave their mark in Dexippus’ commentary on the Categories. Moreover, Dexippus’ commentary and the most comprehensive commentary of all, that of Simplicius , take up Plotinus’ specific objections in detail, along with those of others. This is one of the cases in which the commentators attended to Plotinus closely. As regards Plotinus’ central complaint, that Aristotle’s categories fail to describe the world of intelligibles and Platonic Forms, the replies of Porphyry, Iamblichus and Dexippus are given under the discussion of the first category in 3(d) below.
The controversy of later commentators with Plotinus is not the only one, although it is extremely prominent. Also prominent are Iamblichus’ comments. We see him extending his disagreement with Porphyry. Their dispute on religious matters is well known from Iamblichus’ reply to Porphyry in The Mysteries of the Egyptians. Here, at 302,18-303,30, Iamblichus scolds Porphyry for one of his replies to Plotinus. Iamblichus’ own comments, with which Simplicius does not always agree, sometimes take the form of straight commentary. But he also introduces the neo-Pythagorean treatise on categories by pseudo-Archytas, which he mistakenly takes to antedate and influence Aristotle, and he offers his own higher interpretation, on which more below.
With the whole of Simplicius’ commentary on the Categories now published in translation, along with the commentary of Dexippus, as well as the surviving commentaries of Porphyry and Ammonius , it has now become easier to take in the ancient philosophical critique of Aristotle’s Categories, a critique whose thoroughness is unmatched in the modern literature, although the best modern treatments are informed by it. Further light is likely to be thrown by the Latin commentary of Boethius , which is modelled on Greek commentaries, but we are awaiting the much needed new text from Monika Asztalos.
There is no doubt that Aristotle paid close attention to the right definition of his  first four categories, substance, quantity, quality, relative. But his account of the next ones breaks off after a few lines in ch. 9 of the Categories, and what survives is only the remarks of later commentators on these remaining categories. Moreover, these commentators were taken in by the lines interpolated at llblO-16 which put into Aristotle’s mouth a disclaimer saying the remaining categories require no further discussion. It is true Aristotle may have given them less attention, if Gillespie’s hypothesis above is right. Certainly, the categories of keisthai (posture) and ekhein (having on, or wearing) might not have seemed of equal interest. Nonetheless, Aristotle clearly embarks on a close study of the categories of being an agent or patient before his text breaks off, and the later writers discuss these categories at length and the others.
Plotinus’ treatment of topics in 6.1, though selective, largely follows the same order as Aristotle’s text and consequently of Simplicius’ subsequent commentary. He was very likely following the order of one or more earlier commentaries and critiques. The chief deviations from Simplicius’ order concern the interpolation in Categories ch. 9, where commentators had a freer hand because no discussion by Aristotle survives. Plotinus takes the interpolator’s reference to When and Where and treats it earlier and at some length, because he disagrees with Aristotle on the related topics of time and place. More trivially, he reverses the interpolator’s reference to posture and having on. When it comes to his own concessions in 6.3, he adopts a different order for the four Aristotelian categories he allows, postponing relatives to last.
The replies recorded by Dexippus and Simplicius give us a chance to see how Plotinus fares against his fellow Neoplatonists. He has no equal among the Neo-platonists in the imaginativeness of his treatment of psychology. But on the more cut and dried subject of Aristotle’s categories in application to the sensible world, some of the Neoplatonists are as sharp as he is. Simplicius’ reports of what Plotinus said, even in the apparent quotations, do not always seem to represent Plotinus’ connexion of thought accurately, at least in the version of Plotinus that we have. But it is nonetheless clear that sometimes Plotinus nods, for example, we shall see, in his grasp of Aristotle’s distinction between kinesis and energeia .
Simplicius gives a thumbnail sketch of the main commentators. He thinks the aggressive critique of Lucius and Nicostratus was philosophically fruitful. Plotinus is treated as the most substantial after these, but Porphyry, in his lost commentary on the Categories, addressed to Gedalius, went still further, offering a resolution of every problem that had been raised. Some of this is preserved in the commentaries of Dexippus and Iamblichus, the latter of whom is also fully described, before Simplicius explains his own aspirations.
Simplicius follows Iamblichus’ misidentification of pseudo-Archytas’ work as belonging to Plato’s friend Archytas, and so pre-dating Aristotle.