“The operations are various, and the essence simple, but we say that we know our God from…”

The operations are various, and the essence simple, but we say that we know our God from His operations, but do not undertake to approach near to His essence. His operations come down to us, but His essence remains beyond our reach.

Basil of Caesarea · The Letters · NPNF2 VIII, Letters, Letter CCXXXIV, 1

Answering the Eunomians, who held that a man may know God as God knows Himself. Basil’s distinction — that God is known in what He does and not in what He is — became the load-bearing sentence of Eastern theology, and the text the fourteenth-century argument over the divine energies was fought on.