Fra Angelico (1387–1455). The Annunciation, from the Cortona altarpiece, 1434. Museo Diocesano, Cortona.
"The angel went to her and said, 'Greetings, you who are highly favoured! The Lord is with you.' Mary was greatly troubled at his words and wondered what kind of greeting this might be." Luke 1.28-29.
The Feast of the Annunciation to the Blessed Virgin Mary is celebrated on March 25 each year, nine months before Christmas. 'Annunciation' means 'announcement'. This feast day marks the visit of the angel Gabriel to Mary, telling her that she would be the mother of the Son of God. The feast celebrates God's action in becoming truly human and living in human flesh. It also celebrates Mary’s acceptance of God's action, representing humanity's acceptance of God's gift of salvation in his Son.
The Magnificat (Luke 1:46-55), said regularly at Evening Prayer, is the poem in which Mary responds to the Annunciation and celebrates the power of God.
Salvation to all that will is nigh;
The Song of Mary or Magnificat
My soul proclaims the greatness of the Lord:
There are many musical settings of the Magnificat. Here is one of the very finest. Magnificat (BWV 243) by Johann Sebastian Bach, conducted by Nikolaus Harnoncourt.
And Sabine Baring-Gould's masterful Annunciation hymn, itself the translation of a Basque song:
The angel Gabriel from heaven came,
"For know a blessed Mother thou shalt be,
Then gentle Mary meekly bowed her head,
Of her, Emmanuel, the Christ, was born