What place hath adoption, or the mere conception of a name then, that we should not believe Him to be the Son of God by nature, when He tells us to believe Him to be the Son of God, because the Father’s nature shewed itself in Him by His works? A creature is not equal and like to God: no other nature has power comparable to the divine. He declares that He is carrying on not His own work, but the Father’s, lest in the greatness of the works, the nativity of His nature be forgotten. And as under the sacrament1 of the assumption of a human body in the womb of Mary, the Son of God was not discerned, this must be gathered from His work; But if I do, though ye believe not Me, believe the works. Why doth the sacrament of a human birth hinder the understanding of the divine, when the divine birth accomplishes all its work by aid of the human? Then He tells them what they should gather from His works; That ye may know and believe, that the Father is in Me, and I in Him. The same declaration again, I am the Son of God: I and the Father are one.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: vii. de Trin. 26