Reply Obj. 1: We may consider a twofold order between creatures and God: the first is by reason of creatures being caused by God and depending on Him as on the principle of their being; and thus on account of the infinitude of His power God touches each thing immediately, by causing and preserving it, and so it is that God is in all things by essence, presence and power. But the second order is by reason of things being directed to God as to their end; and it is here that there is a medium between the creature and God, since lower creatures are directed to God by higher, as Dionysius says (Eccl. Hier. v); and to this order pertains the assumption of human nature by the Word of God, Who is the term of the assumption; and hence it is united to flesh through the soul.
Reply Obj. 2: If the hypostasis of the Word of God were constituted simply by human nature, it would follow that the body was nearest to it, since it is matter which is the principle of individuation; even as the soul, being the specific form, would be nearer the human nature. But because the hypostasis of the Word is prior to and more exalted than the human nature, the more exalted any part of the human nature is, the nearer it is to the hypostasis of the Word. And hence the soul is nearer the Word of God than the body is.
Reply Obj. 3: Nothing prevents one thing being the cause of the aptitude and congruity of another, and yet if it be taken away the other remains; because although a thing's becoming may depend on another, yet when it is in being it no longer depends on it, just as a friendship brought about by some other may endure when the latter has gone; or as a woman is taken in marriage on account of her beauty, which makes a woman's fittingness for the marriage tie, yet when her beauty passes away, the marriage tie still remains. So likewise, when the soul was separated, the union of the Word with flesh still endured. _______________________
SECOND ARTICLE [III, Q. 6, Art. 2]
Whether the Son of God Assumed a Soul Through the Medium of the
Spirit or Mind?
Objection 1: It would seem that the Son of God did not assume a soul through the medium of the spirit or mind. For nothing is a medium between itself and another. But the spirit is nothing else in essence but the soul itself, as was said above (I, Q. 77, A. 1, ad 1). Therefore the Son of God did not assume a soul through the medium of the spirit or mind.
Obj. 2: Further, what is the medium of the assumption is itself more assumable. But the spirit or mind is not more assumable than the soul; which is plain from the fact that angelic spirits are not assumable, as was said above (Q. 4, A. 1). Hence it seems that the Son of God did not assume a soul through the medium of the spirit.
Obj. 3: Further, that which comes later is assumed by the first through the medium of what comes before. But the soul implies the very essence, which naturally comes before its power—the mind. Therefore it would seem that the Son of God did not assume a soul through the medium of the spirit or mind.
On the contrary, Augustine says (De Agone Christ. xviii): "The invisible and unchangeable Truth took a soul by means of the spirit, and a body by means of the soul."
I answer that, As stated above (A. 1), the Son of God is said to have assumed flesh through the medium of the soul, on account of the order of dignity, and the congruity of the assumption. Now both these may be applied to the intellect, which is called the spirit, if we compare it with the other parts of the soul. For the soul is assumed congruously only inasmuch as it has a capacity for God, being in His likeness: which is in respect of the mind that is called the spirit, according to Eph. 4:23: "Be renewed in the spirit of your mind." So, too, the intellect is the highest and noblest of the parts of the soul, and the most like to God, and hence Damascene says (De Fide Orth. iii, 6) that "the Word of God is united to flesh through the medium of the intellect; for the intellect is the purest part of the soul, God Himself being an intellect."