  These three types of genera are the ones first introduced by the 5th-century Neoplatonist Ammonius in his commentary on Porphyry’s Isagoge; they are also discussed in Elias’ and David’s commentaries on the same work, in Olympiodorus’ Prolegomena, and in Philoponus’ commentary on Aristotle’s Categories. And it is the same three ways of understanding genera (and species) terms that are discussed by Arethas in his commentary on Porphyry’s Isagoge, but are also hinted at in Photios’ treatise Various Questions for Discussion on Genera and Species (= Amphil. 77) as well as in Psellos’ paraphrase of Aristotle’s De interpretatione.