Among the many Christian customs in anticipation of Christmas, there is one prayer that has come down to us from the Middle Ages called O'Antiphons. The earliest manuscript with the seven O'Antiphons is found in the 11th century. Beginning on the eve of December 18, the monks would chant a different O'Antiphon each evening for seven days. Each antiphon addressed Jesus by a title from the First Testament in anticipation of redemption. The prayers are called O'Antiphons because they begin with the exclamation "O" when addressing the Lord. They are sung before the Canticle of Mary.
O Wisdom O Wisdom, O holy Word of God, you govern all creation with your strong yet tender care. Come and show your people the way to salvation. Based on Wisdom 9:17-18.