Feast transferred from March 25th. Proper on pages 1217 & 403. Preface for the Blessed Virgin Mary on page 884.
This       is the great Festival of the Incarnation, commemorating the announcement       by the Archangel Gabriel to Our Lady that the Divine Son of God, the Word,       would take human nature upon Him in her virginal womb. Its date is       determined by that of Christmas Day, and as the day which marked the       beginning of Christian dispensation it was for many centuries regarded as       the first day of the civil year.
 On       this day the Word was made flesh and dwelt among us, uniting for evermore       our human nature to the Divine nature. The Mystery of the Incarnation       brings vividly before us the boundless condescension and humility of God       the Son in stooping to our condition in order to be our Savior. Equally it       proclaims the glory and greatness of Mary, who was chosen to give to the       Divine Word human flesh and human birth, and so to cooperate with God in       the restoration of mankind. Hence her most glorious title of "Mother       of God," which explains all her glories, her sanctity and her honor.