O Sapienta, ( O Wisdom), you came forth from the mouth of the Most High and reaching from beginning to end, you ordered all things mightily and sweetly. Come and teach us the way of prudence.
O Come, O Wisdom from on high,
Who order all things mightily,
To us the path of knowledge show,
And teach us in her ways to go.
Rejoice! Rejoice, Emmanuel
Shall come to the, O Israel!
From Catholic Culture:
O Antiphons - December 17 - 24
December 17 marks the beginning of the "O" Antiphons, the seven jewels of our liturgy, dating back to the fourth century, one for each day until Christmas Eve. These antiphons address Christ with seven magnificent Messianic titles, based on the Old Testament prophecies and types of Christ. The Church recalls the variety of the ills of man before the coming of the Redeemer.
The "O" Antiphons are the verses for the ancient hymn O Come, O Come Emmanuel. The first letter of the Messianic titles: Emmanuel, Rex, Oriens, Clavis, Radix, Adonai, Sapientia—spell out Latin words ERO CRAS, meaning, "Tomorrow, I will come."
To read more about the O Antiphons, check here and here.