Hilary of Poitiers — as excerpted in the Catena Aurea on Mark 1:1

“(de Trin. iii. 11) He has testified, that Christ was the Son of God, not in name only, but by His own proper nature. We are the sons of God, but He is not a son as we are; for He is the very and proper Son, by origin, not by adoption; in truth, not in name; by birth, not by creation.”