O Emmanuel, Rex et legifer noster,
exspectatio Gentium, et Salvator earum:
veni ad salvandum nos, Domine, Deus noster.
O Emmanuel, our king and our lawgiver,
the hope of the nations and their Saviour:
Come to save us, O Lord our God.
O Virgo virginum, quomodo fiet istud?
Quia nec primam similem visa es nec habere sequentem.
Filiae Jerusalem, quid me admiramini?
Divinum est mysterium hoc quod cernitis.
O Virgin of virgins, how shall this be?
For neither before thee was any like thee, nor shall there be after.
Daughters of Jerusalem, why marvel ye at me?
The thing which ye behold is a divine mystery.
(Alternative Antiphon in English Medieval usage, up to and including the New English Hymnal)
Therefore the Lord himself will give you a sign. Look, the young woman is with child and shall bear a son, and shall name him Immanuel. (Isaiah 7.14)
Come quickly, Lord, and save all that you have made!