Cels. iii. 34, cf. Alexander’s μεσιτεύουσα φύσις μονογενής. But observe that the passage insisted on by Shedd, 294, ἕτερος κατ᾽ οὐσίαν καὶ ὑποκειμένον ὁ υἱ& 232·ς τοῦ πατρός, does not bear the sense he extracts from it. οὐσία here is not ‘essence’ but ‘hypostasis’.