Reference edition:

Manlii Seuerini Boetii, Opera omnia, accurante J.-P. Migne, tomus posterior, Parisiis 1891, 159-294 (Patrologiae Latinae, 64).

At the end of his second commentary on the Isagoge, Boethius tells his readers that he is planning to compose a commentary on Aristotle’s Categories; it is certain that that work was composed after 510 AD, the year in which Boethius was consul, since the preface to the second book mentions that the duties of that office had distracted him from studying philosophy (PL 64: 201; De Rijk 1964).  Boethius claims explicitly in his preface to have been inspired by Porphyry’s work and to have followed the arguments set forth by the Tyrian philosopher (nos nunc Porphyrium sequentes, PL 64: 160); it thus seems likely that he learned the “five voices” from that work (PL 64: 187).  Boethius borrows from Porphyry the idealistic thesis according to which the perceiving intellect and the object perceived are related concepts that imply one another (PL 64: 233) and agrees with him on the need to preserve the Categories’ final chapters (the so-called Postpraedicamenta) since, even if they were added by a later editor, they constitute a necessary complement to Aristotle’s work (PL 64: 263).  Comparison of the two texts reveals that many of Boethius’ views come from Porphyry’s commentary: this is the source from which Boethius draws, for example, the allusion to Herminius, a Greek exegete of the 2^nd c. (PL 64: 212).  It is probable, however, that Boethius did not have direct access to Porphyry’s writings, but rather to a later commentator - such as Iamblichus or Simplicius - who excerpted Porphyry’s work on the Categories (Chadwick 1986).

Boethius’ preface declares his intention to write a second, more detailed commentary on the Categories, just as he did for the Isagoge and the Peri hermeneias; this confirms both that the first commentary constituted a basic introduction to arguments requiring greater effort and that questions related to purpose, utility, and order would have been addressed in alio commentario quem componere proposui de eisdem categoriis ad doctiores (160A).  Although this affirmation is present in Rota’s 1543 edition of Boethius’ text, as well as in later versions that derive from it (viz. Basilea 1546; Migne PL 64), it is not attested in the oldest manuscripts of the Categories or in the first printed editions (Schepps 1897; Brandt 1903; Chadwick 1986).  Moreover, while many manuscripts and some of the first printed editions declare that their version of Boethius’ commentary on the Categories is the author’s Prima Editio, none of them ever mentions a Secunda Editio. A codex housed in Bern’s Burgerbibliothek (Bernensis 363, 9^th c.), however, preserves a fragment of a Latin commentary on the Categories that may come from Boethius’ supposed Secunda Editio; indeed, that text displays many affinities with Iamblichus’ second commentary, which drew on Simplicius (Hadot 1959). 

Boethius’ commentary on the Categories offers its Latin reader a reasonably helpful explanation of the work’s structure and contents.  It makes clear that the ten categories (‘substance,’ ‘quantity,’ ‘qualification,’ ‘relative,’ ‘affecting,’ ‘being-affected,’ ‘when,’ ‘where,’ ‘having,’ and ‘being-in-a-position’) are not merely verbal distinctions or mental conceptions, but describe how things actually are.  After classifying the realities that exist by dividing them between substance and accidents, then between universals (generic or specific) and particulars (individuals), Boethius discusses distinctions between general type, specific type, difference, propriety, and accident.  The second book deals with the problem of ‘quantity,’ a category that embraces a wide variety of arguments; this is followed by a long discussion of ‘relativity,’ defined as an opposing pair of elements that necessarily imply one another and are able to be inverted (e.g. father/son; slave/master).  The third book analyzes ‘quality,’ with a few observations on ‘affecting’ and ‘being affected;’ the remainder of the book pertains strictly to Porphyry and includes Aristotle’s explanation of succinctness related to ‘affecting’ and ‘being-affected,’ which are treated extensively in the De generatione et corruptione and the Physics.  The fourth and final book treats the Postpraedicamenta, opposites, time and simultaneity, change, and ‘having.’  Boethius offers a very precise explanation of Aristotle’s analysis of opposites: some of these are contradictory, while others are not, and some admit intermediary positions (e.g. gray exists between white and black), while others - again - do not (e.g. there is no middle ground between odd and even); lastly, he defines ‘induction’ as a collection of particular cases that is followed by a reduction of them to a universal concept, and concludes with an explication of the types of motion (Chadwick 1986).  [M. Ferroni; tr. C. L. Caterine].