St. Cyril on the Essence of God

St. Cyril of Alexandria ca. 376-444

We see many names predicated of God, but none of them seems to indicate what God is according to essence. Rather, they either show what He is not, or they indicate some condition distinct from another. For example, incorruptible and immortal indicate what He is not; but Father or unbegotten, that He is the begetter, which distinguishes Him from the Son, and that He is not produced; but neither of these is indicative of essence, as I said before, but indicates something of what surrounds the essence. (Treasury of the Holy Trinity: Thesis 31)