34 And Mary said to the angel: How shall this be done, because I know not man?
Ambrose: How subdued her answer is, compared with the words of the Priest [Zacharias]. Then said Mary to the Angel, How shall this be? . . . He [Zacharias] answers, Whereby shall I know this? He refuses to believe that which he says he does not know, and seeks as it were still further authority for belief. She avows herself willing to do that which she doubts not will be done, but how, she is anxious to know.
Gregory of Nyssa: Hear the chaste words of the Virgin. The Angel tells her she shall bear a son, but she rests upon her virginity, deeming her inviolability a more precious thing than the Angel’s declaration. Hence she says, Seeing that I know not a man.
35 And the angel answering, said to her: The Holy Ghost shall come upon thee, and the power of the most High shall overshadow thee. And therefore also the Holy which shall be born of thee shall be called the Son of God.
Chrysostom: Being born from the womb, He shared in common with us, but in that He was born without cohabitation, He was exalted far above us.
Gregory: By the term overshadowing, both natures of the Incarnate God are signified. For shadow is formed by light and matter.
Gregory of Nyssa: He says, overshadow thee, because as a shadow takes its shape from the character of those bodies which go before it, so the signs of the Son’s Deity will appear from the power of the Father.
Basil: There is openly declared a communion of nature between the son and the parent.
Gregory: To distinguish His holiness from ours, Jesus is stated in an especial manner to be born holy. For we although indeed made holy, are not born so, for we are constrained by the very condition of our corruptible nature to cry out with the Prophet, Behold, I was conceived in iniquity.
Scripture from the Douay-Rheims Bible. Commentary from St. Thomas Aquinas, Catena Aurea, Vol. III (London: Rivington, 1843).