(CE:1260a-1261a)
HYPOSTASIS, a word destined to play a large and complicated part in Christian theology from the late third century on. It does not
appear in classical Greek in a philosophical sense but became an important word in Middle Platonism and Neoplatonism. It could mean "that which underlies" (hence it can be used to mean "substance") or "that which gives support" (hence it can be used to mean "individual reality"). At Wisdom 16:12 (the only significant occurrence in the Greek Old Testament) it denotes God's nature, and
this meaning reappears in the expression "impression of [God's] nature" (Heb. 1:3). Elsewhere in the New Testament it means "confidence, assurance, guarantee" (2 Cor. 9:4; 11:17; Heb. 3:14; 11:11).
Until the appearance of the Cappadocian fathers, the word was used indiscriminately to mean "substance" or "individual entity." It
was often taken to be a synonym of ousia (substance), apparently in the anathema of the Nicene Creed (325), which condemns the
doctrine that the Son is of an ousia or hypostasis different from the Father. This equivalence caused endless confusion during the Arian controversy. Eastern theologians were accustomed (following ORIGEN'S usage) to speak of Father, Son, and Holy Spirit as three hypostases. Western theologians tended to think that this meant three diverse substances. The Western bishops at the Council of Sardica (343) declared that God had only one hypostasis. The Easterns consequently suspected the Westerns of SABELLIANISM, while the Westerns in their turn suspected the Easterns of ARIANISM. Athanasius almost always avoided the word hypostasis in trinitarian contexts before 362. In 362 the Council of Alexandria allowed that it was orthodox to think of God as three hypostases, provided this was not intended in an Arian sense, that is, God was not three substances but three "persons." The Cappadocians stereotyped the usage that hypostasis expresses what God is as Three, and ousia what He is as One.
The participants in the disputes concerning the Incarnation, which came to a head in the Chalcedonian formula of 451, also used "hypostasis" extensively to mean "actually existing individual reality" (not "personality"). The Antiochene school (e.g., Nestorius and the more percipient Theodoret of Cyrrhus) tended to hold that in Jesus Christ two different hypostases, the human and the divine, were joined in a moral union, but they found difficulty in explaining what that union produced. The Alexandrian school, notably CYRIL himself, held to a single hypostasis that expressed a single divine-human nature; his term "hypostatic union" meant that the Son of God incarnate represented a single reality in whom the human and the divine were constitutionally, ontologically united. The Chalcedonian formula stated that in Jesus Christ two distinct natures, divine and human, combined, without confusion, in a single prosopon (visible impression) and a single hypostasis (reality), and this union was hypostatic, not merely moral.
R. P. C. HANSON