From Dom Guéranger's The Liturgical Year.
O radix Jesse, qui stas in signum populorum, super quem continebunt reges os suum, quem gentes deprecabuntur: veni ad liberandum nos, jam noli tardare.
O Root of Jesse, who standest as the ensign of the people; before whom kings shall not open their lips; to whom the nations shall pray: come and deliver us; tarry now no more.
At length, O Son of Jesse! Thou art approaching the city of Thy ancestors. The Ark of the Lord has risen, and journeys, with the God that is in her, to the place of her rest. ‘How beautiful are thy steps, O thou daughter of the Prince,’ now that thou art bringing to the cities of Juda their salvation! The angels escort thee, thy faithful Joseph lavishes his love upon thee, heaven delights in thee, and our earth thrills with joy to bear thus upon itself its Creator and its Queen. Go forward, O Mother of God and Mother of men! Speed thee, thou propitiatory that holdest within thee the divine Manna which gives us life! Our hearts are with thee, and count thy steps. Like thy royal ancestor David, ‘we will not enter into the dwelling of our house, nor go up into the bed whereon we lie, nor give sleep to our eyes, nor rest to our temples, until we have found a place in our hearts for the Lord whom thou bearest, a tabernacle for this God of Jacob.’ Come, then, O Root of Jesse! thus hidden in this Ark of purity; Thou wilt soon appear before Thy people as the standard round which all that would conquer must rally. Then their enemies, the kings of the world, will be silenced, and the nations will offer Thee their prayers. Hasten Thy coming, dear Jesus! come and conquer all our enemies, and deliver us.
A Responsory of Advent
(Ambrosian breviary, sixth Sunday of Advent)
R. Beatus uterus Mariæ Virginis qui portavit invisibilem: quem septem throni capere non possunt in eo habitare dignatus est: * Et portabat levem in sinu suo.
V. Dedit illi Dominus sedem David patris sui, et regnabit in domo Jacob in aeternum, cujus regni non erit finis: * Et portabat levem in sinu suo.
R. 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.
V. The Lord hath given him the throne of David his father, and he shall reign in the house of Jacob for ever, and of his kingdom there shall be no end: * And she bore him as a light weight in her womb.
 Cant. vii. 1.
 Ps. cxxxi. 3-5.