Today's O antiphon is O root of Jesse, a reference to the famous concept of the 'Jesse tree' that traces the ancestry of Jesus, and typically key events in salvation history, based on Isaiah 11:
And there shall come forth a rod out of the root of Jesse, and a flower shall rise up out of his root. And the spirit of the Lord shall rest upon him: the spirit of wisdom, and of understanding, the spirit of counsel, and of fortitude, the spirit of knowledge, and of godliness. And he shall be filled with the spirit of the fear of the Lord.
He shall not judge according to the sight of the eyes, nor reprove according to the hearing of the ears. But he shall judge the poor with justice, and shall reprove with equity for the meek of the earth: land he shall strike the earth with the rod of his mouth, and with the breath of his lips he shall slay the wicked. And justice shall be the girdle of his loins: and faith the girdle of his reins.The text of the antiphon itself is:
O Root of Jesse, which standest for an ensign of the people, at whom the kings shall shut their mouths, to whom the Gentiles shall seek; come to deliver us, make no tarrying!Let us therefore pray for the gift of counsel for ourselves and above all for our leaders, that they might discern and follow the path he has flagged, and not some other, and thus avoid judgment and condemnation at the last.