On the Trinity

20. That place of Scripture demands neither a slight nor a passing consideration. For if one man had appeared, what else would those at once cry out, who say that the Son was visible also in His own substance before He was born of the Virgin, but that it was Himself? since it is said, they say, of the Father, “To the only invisible God.” And yet, I could still go on to demand, in what manner “He was found in fashion as a man,” before He had taken our flesh, seeing that his feet were washed, and that He fed upon earthly food? How could that be, when He was still “in the form of God, and thought it not robbery to be equal with God?” For, pray, had He already “emptied Himself, taking upon Him the form of a servant, and made in the likeness of men, and found in fashion as a man?” when we know when it was that He did this through His birth of the Virgin. How, then, before He had done this, did He appear as one man to Abraham? or, was not that form a reality? I could put these questions, if it had been one man that appeared to Abraham, and if that one were believed to be the Son of God. But since three men appeared, and no one of them is said to be greater than the rest either in form, or age, or power, why should we not here understand, as visibly intimated by the visible creature, the equality of the Trinity, and one and the same substance in three persons?

21. For, lest any one should think that one among the three is in this way intimated to have been the greater, and that this one is to be understood to have been the Lord, the Son of God, while the other two were His angels; because, whereas three appeared, Abraham there speaks to one as the Lord: Holy Scripture has not forgotten to anticipate, by a contradiction, such future cogitations and opinions, when a little while after it says that two angels came to Lot, among whom that just man also, who deserved to be freed from the burning of Sodom, speaks to one as to the Lord. For so Scripture goes on to say, “And the Lord went His way, as soon as He left communing with Abraham; and Abraham returned to his place.”