the fire permeates every atom of the iron, clothes it completely, and imparts to the iron something of its own substance and energy, until the iron itself becomes radiant and burning, while the fire takes nothing of the iron’s weakness—neither its darkness nor its coolness.
In precisely this kind of union the creative Word of God devised its conjunction with human nature.
Thus there is one Christ, the only-begotten Son of God, begotten of the Father before all ages: Light from Light, true God from true God, begotten not made, of one substance, essence, and nature with His Father. And yet He is that very same being who, from Mary the Virgin, was born at the end of time in a single person—the person of the only Son of God—uniting within Himself both natures: the divine nature, which has existed from the beginning before every beginning, and the human nature, fashioned at the end of time and established within the eternal person.
He is therefore one Christ in one eternal person, possessing two natures: a divine nature that has always been, and a human nature that He created for Himself and fused with through Mary the Virgin. His person is the person of both the divine and the human nature together, joined without mixture, without corruption, and without any sundering separation. The person of the divine nature has ever existed; it then became also the person of the human nature, which He created, shaped, and sustained in His own person—subsisting only through Him and known only as His.
The reply to this discourse—after first noting that it is self-contradictory—is