Without this freely given assent of Mary, God cannot become man. Certainly, this Yes Mary says is wholly by grace. The dogma of the Immaculate Conception of Mary, whereby she was freed from original sin, has in fact just exactly this as its sole significance: that no human being can set in motion the process of salvation by his own powers alone, but that his Yes is wrapped up and supported within by that divine love which comes first and before all else and that already surrounds man before he is even born. "All is grace". Yet grace does not remove freedom; rather, it brings it into being. The entire mystery of redemption is present in this story and is summed up in the figure of the Virgin Mary: "Behold, I am the handmaid of the Lord; let it be to me according to your word" (Lk 1:38)
From God is Near Us - Pope Benedict XVI.
Please don't forget about this feast...it is so important. What a mystery! What love!