The "O Antiphons" are the great antiphons for the Magnificat hymn of of Vespers, which are said on the seven last days of Advent leading up to Christmas. Each antiphon in Latin begins with a biblical title of Our Lord. The first letters of these antiphons, when arranged from last to first, form the Latin phrase "Ero Cras" which means "Tomorrow I will be there." These antiphons point to the coming of Christ on Christmas Day, and again at the end of time!