Part of singing the Divine Office is to chant The Magnificat each evening at Vespers. And, of course, an antiphon is chanted both before and after. Beginning on December 17th, and continuing until December 23rd, seven very particular and very ancient antiphons are used. They are referred to collectively as the Great Antiphons. Each starts with the exclamation, O, and then refers to Our Lord by a particular title (for example, O Wisdom, or O Dawn). For this reason, they are also known as the O Antiphons. (Note that these antiphons form the basis for the popular hymn, O Come, O Come, Emmanuel.)
Customarily, at the Offertory, we sing hymns dedicated to Our Lady, but at the Communion, we would normally only sing hymns dedicated to Our Lord. Today, we will do otherwise. The O Antiphon for today, December 23rd is O Emmanuel. We will sing that antiphon, then sing The Magnificat, then, naturally, we will repeat the antiphon. Taken together, they are too long for the Offertory, and so we will sing them at the Communion.
The Vigil of the Nativity
Given that the Vigil of the Nativity does not fall on a Sunday, we will not sing the Asperges. And since we will not sing the Asperges, we will be able to commence immediately with the Introit, which we will sing in lieu of a processional. It is the final day of Advent, so we will sing Mass XVII for the last time (until Lent). And, of course, the organ will not be used.
Unlike during Lent, that other penitential season, the Alleluia is sung on Sundays and Feasts during Advent. On most other days during Advent, however, there is no Alleluia, and the rubrics for today’s Mass specify that the Alleluia is to be sung only when the Vigil of the Nativity falls on a Sunday. Thus, we will proceed directly from the Gradual to the Gospel.
The Nativity
Since Christmas does not fall on a Sunday, the Asperges is not sung, and so the Introit will be sung as the processional. We will leave Mass XVII behind until Lent, and will sing Mass II (two), which we will sing throughout the Christmas and Epiphany seasons. During that same period, we will sing Credo III, which, musically speaking, works nicely with Mass II.
Because Christmas is such a great feast, the choir of mixed voices will sing polyphonic pieces at both the Offertory, and the Communion. Noteworthy: At the Communion, we will sing the great piece O Magnum Mysterium, by Tomás Luis de Victoria. This piece takes its text from the Responsory that is sung after Lesson IV of Matins.It is customary at St. Anthony’s, to sing Angels we Have Heard on High as the recessional, and so we will continue with that tradition.