O Radix Jesse

O Root of Jesse, who stands as the ensign of the people; before whom kings shall fall silent; to whom the nations shall pray: come and deliver us, do not delay.

Here is commentary from Fr. Mark:

O Root of Jesse

The image of the Root of Jesse comes from the eleventh chapter of Isaiah where he says, “And there shall come forth a rod out of the root of Jesse, and a flower shall rise up out of His root” (Is 11:1). It is the passage that enumerates the gifts of the Holy Ghost; from the Vulgate, the Catholic tradition counts seven gifts. “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” (Is 11:2-3). This means that when we cry out, “Come,” to the Root of Jesse who is Christ, we are, in the same prayer, invoking the Holy Ghost who, in His sevenfold gift, comes to us with the Son.

The Tree of the Cross

Isaiah goes on to say in the tenth verse of the same chapter: “On that day the root of Jesse shall stand as a signal to the peoples; the nations shall inquire of Him.” The Root of Jesse is given, not only to Israel, but as a signal to the nations, a standard around which all peoples will rally. In fulfillment of Isaiah’s prophecy, Jesus says of himself, “And I, when I am lifted up from the earth, will draw all men to myself” (Jn 12:32). The Root of Jesse is already the profile of the Cross: a figure of the glorious standard of the King, the Vexilla Regis of which we sing in the Vespers hymn of September 14th. Today’s O Antiphon opens onto the paschal mystery: the Root of Jesse announces that the advent of the Son is ordered to the mission of redemption that He will accomplish on the Tree of the Cross.

 

Here is a quote from the ancient Ambrosian liturgy:

Blessed is the womb of the Virgin Mary, which bore the invisible God.
There did he deign to dwell, whom seven thrones cannot hold
And she bore him as a light weight in her womb.
(from Dom Gueranger's The Liturgical Year, Vol I)