After the flashing of the shining cloud, thus the sweet and terrible voice of the eternal Father thunders over the Son: This is my beloved Son, in whom I am well pleased: hear Him (Matt. XVII, 5). We are all indeed, as the Apostle says, sons of God (Gal. III, 26), and in prayer we presume to cry, Our Father, who art in heaven. But otherwise is He a Son of whom it is cried, This is my beloved Son. For the Father to have Him as Son, no will preceded the generation; but we, through that by which we are made sons, receive our birth in the font. And therefore whatever man can be a son of God, can also not be.
Whence John the evangelist says, that He gave them power to become sons of God, to those who believe in His name (John I, 12); so that one either remains a son by living well, or certainly by carnal conversation casts off the sonship. But Christ, whom not grace but nature made the Son of God the Father, can in no way not be that which He was begotten; so much so that He would prejudice not even that substance which is born of man against that which proceeds from God.