On the contrary, Is the authority of Felix, Pope and Martyr, which is quoted by the Council of Ephesus: "We believe in our Lord Jesus Christ, born of the Virgin Mary, because He is the Eternal Son and Word of God, and not a man assumed by God, in such sort that there is another besides Him. For the Son of God did not assume a man, so that there be another besides Him."
I answer that, As has been said above (A. 2), what is assumed is not the term of the assumption, but is presupposed to the assumption. Now it was said (Q. 3, AA. 1, 2) that the individual to Whom the human nature is assumed is none other than the Divine Person, Who is the term of the assumption. Now this word "man" signifies human nature, as it is in a suppositum, because, as Damascene says (De Fide Orth. iii, 4, 11), this word God signifies Him Who has human nature. And hence it cannot properly be said that the Son assumed a man, granted (as it must be, in fact) that in Christ there is but one suppositum and one hypostasis. But according to such as hold that there are two hypostases or two supposita in Christ, it may fittingly and properly be said that the Son of God assumed a man. Hence the first opinion quoted in Sent. iii, D. 6, grants that a man was assumed. But this opinion is erroneous, as was said above (Q. 2, A. 6).
Reply Obj. 1: These phrases are not to be taken too literally, but are to be loyally explained, wherever they are used by holy doctors; so as to say that a man was assumed, inasmuch as his nature was assumed; and because the assumption terminated in this—that the Son of God is man.
Reply Obj. 2: The word "man" signifies human nature in the concrete, inasmuch as it is in a suppositum; and hence, since we cannot say a suppositum was assumed, so we cannot say a man was assumed.
Reply Obj. 3: The Son of God is not the man whom He assumed, but the man whose nature He assumed. _______________________
FOURTH ARTICLE [III, Q. 4, Art. 4]
Whether the Son of God Ought to Have Assumed Human Nature Abstracted from All Individuals?
Objection 1: It would seem that the Son of God ought to have assumed human nature abstracted from all individuals. For the assumption of human nature took place for the common salvation of all men; hence it is said of Christ (1 Tim. 4:10) that He is "the Saviour of all men, especially of the faithful." But nature as it is in individuals withdraws from its universality. Therefore the Son of God ought to have assumed human nature as it is abstracted from all individuals.
Obj. 2: Further, what is noblest in all things ought to be attributed to God. But in every genus what is of itself is best. Therefore the Son of God ought to have assumed self-existing (per se) man, which, according to Platonists, is human nature abstracted from its individuals. Therefore the Son of God ought to have assumed this.
Obj. 3: Further, human nature was not assumed by the Son of God in the concrete as is signified by the word "man," as was said above (A. 3). Now in this way it signifies human nature as it is in individuals, as is plain from what has been said (A. 3). Therefore the Son of God assumed human nature as it is separated from individuals.