On the floor of the holy house in Nazareth, an inscription reads “Verbum caro hic factum est” (“the Word was made flesh here.”) When the Blessed Virgin said “yes” to the Angel Gabriel, the Word became flesh and dwelt in her womb for nine months. The Annunciation is the prologue to the mysteries of Holy Week: the Incarnation happened so that we could be redeemed; the child conceived on this day was born to die for our sins and conquer death. – CTS New Daily Roman Missal 2012, p 2619.
The Feast of the Annunciation of the Blessed Virgin Mary dates back to at least the 6th century, and is mentioned between AD 530 and 533 in a sermon by Abraham of Ephesus. In the West, the first authentic reference is in the Gelasian Sacramentary in the 7th century. The tenth Synod of Toledo (AD 656), and Trullan Synod (AD 692) speak of the Annunciation feast as universally celebrated in the Catholic Church. In the Acts of the latter council, the feast is exempted from the Lenten fast.