O Emmanuel - (O Emmanuel) - O Antiphon for December 23
O Emmanuel, king and lawgiver,
desire of the nations, Savior of all people: Come and set us free, Lord our God.
Rex et legifer noster, expectatio gentium, et Salvator earum:veni ad salvandum nos, Domine, Deus noster.
The first letters of the titles, from last to first, appear to form a Latin acrostic, 'Ero cras', meaning 'Tomorrow, I will be [there]', mirroring the theme of the antiphons. This is formed from the first letter of each title – Emmanuel, Rex, Oriens, Clavis, Radix, Adonai, Sapientia.
And the Song You All Know!
The song, O Come, O Come Emmanuel is also based in the O Antiphons!