Whether the union of the Incarnation took place by grace?

Objections

Objection 1 : It would seem that the union of the Incarnation did not take place by grace. For grace is an accident, as was shown above (FS, Question [110], Article [2]). But the union of the human nature to the Divine did not take place accidentally, as was shown above (Article [6]). Therefore it seems that the union of the Incarnation did not take place by grace.
Objection 2 : Further, the subject of grace is the soul. But it is written (Col. 2:9): "In Christ [Vulg.: 'Him'] dwelleth all the fulness of the Godhead corporeally." Therefore it seems that this union did not take place by grace.
Objection 3 : Further, every saint is united to God by grace. If, therefore, the union of the Incarnation was by grace, it would seem that Christ is said to be God no more than other holy men.