"...It was reasonable that it should be announced to the Blessed Virgin that she was to conceive Christ. First, in order to maintain a becoming order in the union of the Son of God with the Virgin—namely, that she should be informed in mind concerning Him, before conceiving Him in the flesh. Thus Augustine says (De Sancta Virgin. iii): "Mary is more blessed in receiving the faith of Christ, than in conceiving the flesh of Christ"; and further on he adds: "Her nearness as a Mother would have been of no profit to Mary, had she not borne Christ in her heart after a more blessed manner than in her flesh."
"Secondly, that she might be a more certain witness of this mystery, being instructed therein by God.
"Thirdly, that she might offer to God the free gift of her obedience: which she proved herself right ready to do, saying: "Behold the handmaid of the Lord."
"Fourthly, in order to show that there is a certain spiritual wedlock between the Son of God and human nature. Wherefore in the Annunciation the Virgin's consent was besought in lieu of that of the entire human nature."
~St. Thomas Aquinas: Summa Theologiae, III, Q. 30, Art. 1.
Annunciation, by Fra Angelico. Panel, 1430's;
Santa Maria delle Grazie, San Giovanni Valdarno.
