Note 578 — Lecture IX. GREEK AND CHRISTIAN THEOLOGY. III. God as the Supreme Being.

Ath. Dial. de Trin. 2: ἡ οὐσία τὴν κοινότητα σημαίνει, while ὑπόστασις ἰδιότητα ἔχει ἥτις οὔκ ἐστι κοινὴ τῶν τῆς αὐτῆς οὐσίας ὑποστάσεων. He elsewhere identifies it with πρόσωπον in Ath. et Cyril. in Expos. orthod. fid.: ὑπόστασις ἐστιν οὐσία μετά τινων ἰδιωμάτων ἀριθμῷ τῶν ὁμοειδῶν διαφέρουσα· τουτέστι πρόσωπον ὁμοούσιον. Still the identity of the two terms was allowed even after they were tending to be differentiated: cf. Athan. ad Afr. Ep. 4, vol. i. 714, ἡ δὲ ὑπόστασις οὐσία ἐστι καὶ οὐδὲν ἄλλο σημαινόμενον ἔχει ἢ αὐτὸ τὸ ὄν. So ad Antioch., 6. (i. 617), he tolerates the view that there was only one ὑπόστασις in the Godhead, on the ground that ὑπόστασις might be regarded as synonymous with οὐσία. Cf. objection at Council of Sardica, against three ὑποστάσεις in the Godhead, instead of one ὑπόστασις, of Father, Son and Spirit.