In the Annunciation, the birth of the Son of God in the flesh is made to hinge on the consent of a woman, as the fall of man in the garden of paradise hinged on the consent of a man. God in His power might have assumed a human nature by force, as the hand of a man lays hold of a rose. But He willed not to invade His great gift of freedom without a creature’s free response. Through the angel who salutes Mary in words that have become the first part of the Hail Mary, ‘Hail, full of grace, the Lord is with thee,” Mary is asked if she will give God a man! Mary learning that she will conceive without human love, but with the overshadowing of divine Love, consents, and a new humanity begins, with Mary as the new Eve, and Christ the new Adam.
The Annunciation is the Mystery of the joy of freedom. Our free will is the only thing in the world that is our own. God can take away anything else, our health, wealth, power, but God will never force us to love Him or to obey Him. The charm of Yes is in the possibility that one might have said No. Mary has taught us to say Fiat to God. ‘Be it done to me according to Thy word.’ But God Himself has taught us that if He would not invade the freedom of a woman, then a man should never do it.
– Archbishop Fulton Sheen (The Fifteen Mysteries)