We are now in the final days of Advent, in which the famous "O" Antiphons are sung each day at Vespers with the Magnificat. These are one of the most loved features of the Church's liturgy, and for good reason; the texts are especially rich in references to the Old Testament prophecies of the Divine Redeemer and His coming for the salvation of the human race, and the Gregorian chant with which they are sung is extremely beautiful. The Roman Rite has seven of these, and it of course well known that the first letters of the seven titles (O Sapientia, O Adonai etc.) form an acrostic when read backwards, ERO CRAS, Latin for "Tomorrow I will be."; this is completed on the last day before the Christmas season formally begins on the evening of the 24th.
Magnificat antiphon. Various other particular customs were observed in other places. In the very ancient abbey of Fleury, the intonation of each antiphon was assigned to a particular member of the monastery: O Wisdom to the abbot, O Lord to the prior, O Root of Jesse to the gardener, O Key of David to the cellarer, (who held the key to all of the storehouses), etc. (Martene 'De antiquis Ecclesiae ritibus' IV.3.3) The medieval use of Augsburg Cathedral in Germany contains a particularly interesting enrichment of the liturgy on these days. Each O is accompanied by a special chapter, and a special concluding oration, both of which refer back to it; these form a kind of scriptural and euchological commentary on the much older antiphons. Like many medieval uses, that of Augsburg also added other antiphons to the series, which I will note in another post later this week; here are the chapters and prayers which go with the seven oldest antiphons, those found in the Roman Breviary. At Augsburg, the Os began on December 13th, and so I have noted them here.
The translations of the Scriptural passages are taken from the Douay-Rheims version; where the quotation is different from the actual words of Scripture (a common enough feature of medieval liturgical texts), I have placed the changed words in italics. The translations of the antiphons are based on those in the English version of the Roman Breviary by the Marquess of Bute, with many modifications; those of the prayers are my own. It should be noted that the Chapter which accompanies "O Radix Jesse" is based on Isaiah 11, 10, but is actually quoted from a responsory of the Third Sunday of Advent. Likewise, the prayer which accompanies "O Clavis David" is that of the Third Sunday of Advent, and that which accompanies "O Rex gentium" is that of the First Sunday.