O Emmanuel, our King and Lawgiver, longing of the nations and Savior thereof: Come and save us, O Lord our God.
This is the last of the "O Antiphons" from the office of Vespers (AKA Evening Prayer) which precede and follow the Magnificat, that great canticle of the Blessed Virgin Mary. For seven days preceding the Vigil of Christmas, they are placed in the Divine Office so that we might call upon the Lord to come and more fully prepare ourselves in joy for His coming.
Next year I think I will do the antiphons each day but as NLM and others have done that this year, it's a bit redundant.
What I find fascinating is this. From NLM
If one starts with the last title and takes the first letter of each of the O Antiphons - Emmanuel, Rex, Oriens, Clavis, Radix, Adonai, Sapientia - the Latin words ero cras are formed, meaning, “Tomorrow, I will come.”In the Sarum Use the antiphons begin on the 16th, not the 17th, and so the acrostic is different and still very fascinating. Again, I'll hit at it next Advent, and I shall bring Introduction to Christianity home with me, because YHWH's other possible translations are very similar in concept to Emmanuel.
I hope Advent has been a very fruitful season.