Note 110 — Chapter III · CATEGORIÆ.
Reading edition
Metaphysic. Δ. p. 1020, b. 13: σχεδὸν δὴ κατὰ δύο τρόπους λέγοιτ’ ἂν τὸ ποιόν, καὶ τούτων ἕνα τὸν κυριώτατον· πρώτη μὲν γὰρ ποιοτὴς ἡ τῆς οὐσίας διαφορά. Compare Physic. v. p. 226, a. 27. See Trendelenburg, Kategorienlehre, pp. 56, 93.
The remarks of the different expositors (contained in Scholia, pp. 52, 53, 54, Brand.), are interesting upon the ambiguous position of Differentia, in regard to Substance and Quality. It comes out to be Neither and Both — οὐδέτερα καὶ ἀμφότερα (Plato, Euthydemus, p. 300 C.). Dexippus and Porphyry called it something intermediate between οὐσία and ποιότης, or between οὐσία and συμβεβηκός.