Reply 1. The Incarnation does not mean either the conversion of the Word into flesh, or the union of the Word with a human body as the form of the same.
Arg. 2. If the person of the Word of God acquires a new subsistence in a human nature, it must undergo a substantial change, as everything is changed that acquires a new nature.
Reply 2. The change is not in the Word of God, but in the human nature assumed by the Word.
Arg. 3. If the personality of the Word of God has become the personality of a human nature, it follows that since the Incarnation the Word of God has not been everywhere, as that human nature is not everywhere.
Reply 3. Personality does not extend beyond the bounds of that nature from which it has its subsistence. But the Word of God has not its subsistence from its human nature, but rather draws that human nature to its own subsistence or personality: for it does not subsist through it, but in it.
Arg. 4. One and the same thing has only one quiddity, substance, or nature. It seems impossible therefore for one person to subsist in two natures.
Reply 4. The assertion is true, if you speak of the nature whereby a thing has being, absolutely speaking; and so, absolutely speaking, the Word of God has being by the divine nature alone, not by the human nature. But by the human nature it has being as Man.
Arg. 8. Soul and body in Christ are of not less potency than they are in other men. But their union in other men constitutes a person: therefore also in Christ.
Reply 8. The human soul and body in Christ being drawn into the personality of the Word, and not constituting another person besides the person of the Word, does not mark a diminution of potency, but a greater excellence. Everything is better for being united to what is more excellent than itself, better than it was, or would be, if it stood by itself.*
Arg. 10. This man, who is Christ, considered merely as made up of soul and body, is a substance: but not a universal, therefore a particular substance: therefore a person.
Reply 10. Yes, He is a person, but no other person than the person of the Word: because the human nature has been so assumed by the person of the Word that the Word subsists as well in the human as in the divine nature: but what subsists in human nature is 'this man': therefore the Word Himself is spoken of* when we say 'this Man.'
Arg. 11. If the personality of the divine and human nature in Christ is the same, divine personality must be part of the notion of the Man who is Christ. But it is not part of the notion of other men. Therefore the application of the common term 'man' to Christ and to other men is an instance of the use of the same term not in the same sense; and thus He will not be of the same species with us.
Reply 11. Variation of the sense of a term comes from diversity of form connoted, not from diversity of person denoted. The term 'man' does not vary in sense by denoting sometimes Plato, sometimes Socrates.* The term 'man' then, whether used of Christ or of other men, always connotes the same form, that is, human nature, and is predicated of them all in the same sense. But the denotation varies in this that, as taken for Christ, the term denotes an uncreated person; but as taken for other men, a created person.
4.41 : Some further Elucidation of the Incarnation
4.44 : That the Human Nature, assumed by the Word, was perfect in Soul and Body in the instant of Conception