This is the ancient title for the feast celebrating the Incarnation of the Word. This feast is a joint celebration of Christ and the Blessed Virgin: of the Word who becomes the Son of Mary and of the virgin who becomes the Mother of God.
In the universal Church, this liturgy celebrates the beginning of redemption. It also honours Mary as the ‘new Eve’, the obedient and faithful woman who generously agrees to be the Mother of God. Mary cooperates freely in the plan of salvation.