qui Moysi in igne flammae rubi apparuisti,
et ei in Sina legem dedisti:
veni ad redimendum nos in brachio extento.
O Adonai, and leader of the House of Israel,
who appeared to Moses in the fire of the burning bush
and gave him the law on Sinai:
Come and redeem us with an outstretched arm.
From the 17th to the 23rd of December, in the final days of Advent, the antiphons for the Magnificat at Vespers are particularly elaborate. Each antiphon is a title of the Messiah, and each refers to one of Isaiah’s prophecies of the Messiah.
These “O Antiphons”, in metrical form, comprise the verses of the familiar Christmas hymn, “O come, o come, Emmanuel”. The initials of the second word in each antiphon (“Sapientia”, “Adonai”, et cetera), taken in reverse order, form the acrostic ero cras, meaning “Tomorrow, I will be [there]”.