From Dom Guéranger's The Liturgical Year.
Regem venturum Dominum, venite, adoremus.
De Isaia Propheta.
Lavamini, mundi estote, auferte malum cogitationum vestrarum ab oculis meis: quiescite agere perverse, discite benefacere: quaerite judicium, subvenite oppresso, judicate pupillo, detendite viduam. Et venite, et arguite me, dicit Dominus. Si fuerint peccata vestra ut coccinum, quasi nix dealbabuntur: et si fuerint rubra quasi vermiculus, velut lana alba erunt.
Come, let us adore the King our Lord, who is to come.
From the Prophet Isaias.
Wash yourselves, be clean, take away the evil of your devices from my eyes: cease to do perversely, learn to do well; seek judgement, relieve the oppressed, judge for the fatherless, defend the widow. And then come, and accuse me, saith the Lord. If your sins be as scarlet, they shall be made as white as snow; and if they be red as crimson, they shall be white as wool.
The Saviour, who is so soon to be with us and to save us, warns us not only to prepare ourselves to appear before Him, but also to purify our souls. ‘It is most just,’ says St. Bernard, ‘that the soul, which was the first to fall, should be the first to rise. Let us therefore defer caring for the body, until the day when Jesus Christ will come and reform it by the Resurrection; for, in the first coming, the Precursor says to us: “Behold the Lamb of God, who taketh away the sins of the world.” Observe, he says not the maladies of the body, nor the miseries of the flesh; he says sins, which are the malady of the soul, and the corruption of the spirit. Take heed, then, thou my body, and wait for thy turn and time. Thou canst hinder the salvation of the soul, and thine own safety is not within thy reach. Let the soul labour for herself, and strive thou too to help her, for if thou sharest in her sufferings thou wilt share in her glory. Retard her perfection, and thou retardest thine own. Thou wilt not be regenerated until God sees His own image restored in the soul.’ Let us, then, purify our souls. Let us do the works of the spirit, not the deeds of the flesh. Our Saviour’s promise is most clear; He will turn the deep dye of our iniquities into the purest whiteness. He asks but one thing of us: that we sin no more. He says to us: ‘Cease to do perversely, and then come and accuse Me, come and complain against Me, if I do not cleanse you.’ O Jesus! we will not defer a single day of this holy season; we accept, from this moment, the conditions Thou offerest us. We sincerely desire to make our peace with Thee; to bring the flesh into subjection to our spirit, to make good all the injustice we have committed against our neighbour, and to hush, by the sighs of our heart-felt compunction, that voice of our sins which has so long cried to Thee for vengeance.
Prose for the Time of Advent
(Composed in the eleventh century, and taken from the ancient Roman-French missals)
Salus æterna, indeficiens mundi vita.
Lux sempiterna, et redemptio vera nostra.
Condolens humana perire sæcla per tentantis numina.
Non linquens excelsa, adisti ima propria elementia.
Mox tua spontanea gratia assumens humana,
Quae fuerant perdita omnia, salvasti terrea.
Ferens mundo gaudia.
Tu animas et corpora nostra, Christe, expia,
Ut possideas lucida nosmet habitacula.
Adventu primo justifica.
In secundo nosque libera;
Ut cum facta luce magna, judicabis omnia,
Compti stola incorrupta, nosmet tua subsequamur mox vestigia quocumque visa. Amen.
Thou our eternal salvation, the never-failing light of the world.
Light everlasting and our true redemption.
Moved with compassion to see the human race perish by its idolatry offered to its very tempter.
Thou didst descend to these depths of our misery, yet not leaving thine own high throne above.
Then, by thy own gratuitous love, assuming our human nature,
Thou didst save all on earth that was lost,
Giving joy to this world.
Come, O Christ, purify our souls and bodies.
And make them thy own pure abode.
Justify us by thy first coming.
And in thy second, deliver us;
That so, when thou judgest all things, on the day of the great light,
We may be adorned with a spotless robe, and may follow thy footsteps wheresoever they are seen. Amen.
Prayer from the Ambrosian Breviary
(Second Sunday of Advent)
Dona, quæsumus, omnipotens Deus, cunctae familiae tuæ hanc voluntatem, Christo Filio tuo, Domino nostro venienti, in operibus justis apte occurrere: ut ejus dexterae sociati, regnum mereamur possidere cœleste. Per eumdem Christum Dominum nostrum. Amen.
O almighty God! grant, we beseech thee, unto all this thy family, the desire of meeting, by good works, thy Son, Christ our Lord, who is coming to us; that being placed on his right hand, we may deserve the possession of the heavenly kingdom. Through the same Christ our Lord. Amen.
 Sixth Sermon of Advent.