St. Simon of Cyrene Orthodox Mission
"In both the Cappadocian and Alexandrian (icon) traditions the ousia [Substance] of God is beyond all categories of thought in a radical manner and therefore not only beyond definition of any kind, but also beyond the predication of any name whatsoever, to such an extent that God is hyper-onymos, hyper-ousios and even hyper-theos.
Within this Biblical tradition the ousia of man also remains a mystery. Only the energies and powers of both God and man can be known. In this sense the term ousia is used not in the Greek philosophical sense of the definable and knowable immutable inner reality of a thing, but as concrete unknowable reality known only in its acts.
In contrast to the Antiochene and Latin tradition (the Augustinian one), the term ousia as applied to the Holy Trinity by the Cappadocian and Alexandrian Fathers is neither a platonic superstratal genus, nor an Aristotelian substratal material in which the hypostases or persons of the Holy Trinity participate. Therefore, Christ being in two ousiai could only mean that our Lord, the Only-Begotten Son of God, exists in two concrete, yet undefinable and perfect and complete realities, each of which is by nature proper to Himself and distinguishable in the union in thought alone."
--Fr. John Romanides
God the Holy Trinity: ‘The Lover of Mankind’ (& the "depiction of God" in Orthodox Church)
Utatu Mtakatifu, Mungu ambaye anapenda ubinadamu