on. Now to be the principle of the assumption belongs to the
Divine Nature in itself, because the assumption took place by Its
power; but to be the term of the assumption does not belong to the
Divine Nature in itself, but by reason of the Person in Whom It is
considered to be. Hence a Person is primarily and more properly said
to assume, but it may be said secondarily that the Nature assumed a
nature to Its Person. And after the same manner the Nature is also
said to be incarnate, not that it is changed to flesh, but that it
assumed the nature of flesh. Hence Damascene says (De Fide Orth. iii,
6): "Following the blessed Athanasius and Cyril we say that the
Nature of God is incarnate."

Reply Obj. 1: "Oneself" is reciprocal, and points to the same
suppositum. But the Divine Nature is not a distinct suppositum from
the Person of the Word. Hence, inasmuch as the Divine Nature took
human nature to the Person of the Word, It is said to take it to
Itself. But although the Father takes human nature to the Person of
the Word, He did not thereby take it to Himself, for the suppositum
of the Father and the Son is not one, and hence it cannot properly be
said that the Father assumes human nature.

Reply Obj. 2: What is befitting to the Divine Nature in Itself is
befitting to the three Persons, as goodness, wisdom, and the like.
But to assume belongs to It by reason of the Person of the Word, as
was said above, and hence it is befitting to that Person alone.

Reply Obj. 3: As in God _what is_ and _whereby it is_ are the same,
so likewise in Him _what acts_ and _whereby it acts_ are the same,
since everything acts, inasmuch as it is a being. Hence the Divine
Nature is both that whereby God acts, and the very God Who acts.
_______________________

THIRD ARTICLE [III, Q. 3, Art. 3]

Whether the Nature Abstracted from the Personality Can Assume?

Objection 1: It would seem that if we abstract the Personality by our
mind, the Nature cannot assume. For it was said above (A. 1) that it
belongs to the Nature to assume by reason of the Person. But what
belongs to one by reason of another cannot belong to it if the other
is removed; as a body, which is visible by reason of color, without
color cannot be seen. Hence if the Personality be mentally
abstracted, the Nature cannot assume.

Obj. 2: Further, assumption implies the term of union, as was said
above (A. 1). But the union cannot take place in the nature, but only
in the Person