not follow but rather preceded the union.

Obj. 3: Further, the common precedes the proper. But habitual grace
is common to Christ and other men; and the grace of union is proper
to Christ. Therefore habitual grace is prior in thought to the union.
Therefore it does not follow it.

_On the contrary,_ It is written (Isa. 42:1): "Behold my servant, I
will uphold Him . . . "and farther on: "I have given My Spirit upon
Him"; and this pertains to the gift of habitual grace. Hence it
remains that the assumption of human nature to the unity of the
Person preceded the habitual grace of Christ.

_I answer that,_ The union of the human nature with the Divine
Person, which, as we have said above (Q. 2, A. 10; Q. 6, A. 6), is
the grace of union, precedes the habitual grace of Christ, not in
order of time, but by nature and in thought; and this for a triple
reason: First, with reference to the order of the principles of both.
For the principle of the union is the Person of the Son assuming
human nature, Who is said to be sent into the world, inasmuch as He
assumed human nature; but the principle of habitual grace, which is
given with charity, is the Holy Ghost, Who is said to be sent
inasmuch as He dwells in the mind by charity. Now the mission of the
Son is prior, in the order of nature, to the mission of the Holy
Ghost, even as in the order of nature the Holy Ghost proceeds from
the Son, and love from wisdom. Hence the personal union, according to
which the mission of the Son took place, is prior in the order of
nature to habitual grace, according to which the mission of the Holy
Ghost takes place. Secondly, the reason of this order may be taken
from the relation of grace to its cause. For grace is caused in man
by the presence of the Godhead, as light in the air by the presence
of the sun. Hence it is written (Ezech. 43:2): "The glory of the God
of Israel came in by the way of the east . . . and the earth shone
with His majesty." But the presence of God in Christ is by the union
of human nature with the Divine Person. Hence the habitual grace of
Christ is understood to follow this union, as light follows the sun.
Thirdly, the reason of this union can be taken from the end of grace,
since it is ordained to acting rightly, and action belongs to the
suppositum and the individual. Hence action and, in consequence,
grace ordaining thereto, presuppose the hypostasis which operates.
Now the hypostasis did not exist in the human natur