Here are some of the readings from the Office of Matins for this feast, which is celebrated on October 11 in the "old" calendar. It seems to me that we have lost so much by the revision of the calendar which omits so many feasts! By celebrating our saints during the week, as well as on Sundays, we keep our hearts and minds on the things of God; it’s a reminder that the things of the world are fleeting and superficial, and that our true home is Heaven.
From the Acts of Pope Pius XI
In the year 1931, amid the applause of the whole Catholic world, solemn rites were celebrated to mark the completion of the fifteen centuries which had elapsed since the Council of Ephesus, moving against the Nestorian heresy, had acclaimed the Blessed Virgin Mary, of whom Jesus was born, as Mother of God. This acclamation had been made by the Fathers of the Church under the leadership of Pope Celestine. Pius XI, as Supreme Pontiff, wished to commemorate the notable event and to give lasting proof of his devotion to Mary.