We continue with the difficulties of the Incarnation.
1 However, since the Word assumed the human nature into a unity of person (this is clear from the things already said), necessarily the human nature did not pre-exist before its union to the Word.
2 Now, if it were pre-existing, since a nature cannot preexist except in an individual, there would have had to be some individual of that human nature pre-existing before the union. But the individual of human nature is an hypostasis and person. Then one will be saying that the human nature to be assumed by the Word had pre-existed in some hypostasis or person.
If, then, that nature had been assumed with the previous hypostasis or person remaining, two hypostases or persons would have remained after the union: one of the Word, the other of a man. And thus the union would not have taken place in the hypostasis or person. This is contrary to the teaching of the faith.
But if that hypostasis or person in which the nature to be assumed by the Word had pre-existed were not remaining, this could not have happened without corruption, for no singular ceases to be what it is except through corruption. Thus, then, would that man have had to be corrupted who pro-existed the union and, in consequence, the human nature, as well, which was existing in him. It was impossible, then, that the Word assume into a unity of person some preexisting man.
3 But at the same time it would detract from the perfection of the incarnation of God’s Word, if something natural to man were lacking to it. But it is natural to man to be born in a human birth. But God’s Word would not have this if He had assumed a pre-existing man, for that man in his birth would have existed as pure man, and so his birth could not be attributed to the Word, nor could the Blessed Virgin be called the Mother of the Word.
But what the Catholic faith confesses regarding natural things is that He is “in all things like as we are, without sin” (Heb. 4:15); and it says that the Son of God was “made of a woman,” following the Apostle (Gal. 4:4), that He was born and that the Virgin is the Mother of God. This, then, was not seemly, that He assume a pre-existing man.
4 Hence, also, it is clear that from the first moment of conception He united human nature to Himself. Just as God’s Word’s being human demands that the Word of God be born by a human birth, in order to be a true and natural man in complete conformity with us in respect to nature, so, too, it requires that God’s Word be conceived by a human conception, for, in the order of nature, no man is born unless first he be conceived.
But, if the human nature to be assumed had been conceived in any state whatever before it was united to the Word, that conception could not be so attributed to the Word of God that one might call Him conceived by a human conception. Necessarily, then, from the first moment of conception the human nature was united to the Word of God.
5 Again, the active power in human generation acts toward the completion of human nature in a determined individual. But, if the Word of God had not assumed human nature from the first moment of His conception, the active power in the generation would, before the union, have ordered its action to an individual in human nature, and this is a human hypostasis or person. But after the union the entire generation would have had to be ordered to another hypostasis or person, namely, to God’s Word who was being born in the human nature.
Arid such a generation would not have been numerically one, if thus ordered to two persons. Neither would it, in its entirety have been one in form; this seems foreign to the order of nature. Therefore, it was not suitable that the Word of God assume human nature after the conception, but in the conception itself.
6 Once again, this seems to be required by the order of human generation: the one who is born must be the same as the one conceived, not another, for conception is ordered to birth. Hence, if the Son of God was born by a human birth, it must be that it was the Son of God who was conceived in a human conception, and not a pure man.