Thomas Aquinas,
Summa Theologiae — Question 7 - OF THE GRACE OF CHRIST AS AN INDIVIDUAL MAN…
“ 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. ”
