Today is Thursday in the fourth week of Advent and is of simple rite.
At Mattins in the nocturn psalms 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78 & 79 are sung under the six antiphons appointed for Thursdays. The lessons are from the Prophet Isaiah. The third lesson is extended by the inclusion of v. 12, the last verse of chapter 64, which is omitted in the later editions. At Lauds the ferial psalms are sung: 50, 89, 62-66, Cantemus Domino & 148-149-150. These are sung under the antiphons De Sion etc for the Thursday before the Vigil of the Nativity. The antiphon on the Benedictus is proper to the day Ecce completa sunt omnia, quae dicta sunt per Angelum de Virgine Maria. The ferial preces are sung, kneeling, with the psalm De profundis.
At Prime the first antiphon of Lauds is sung, the psalmody is 53, 21, 118(i) & 118(ii). The ferial preces are sung, again kneeling, at all the Hours. The antiphons from Lauds are sung with the other Hours in due order.
Mass is sung after None. The ministers wear folded chasubles. The Mass of the Fourth Sunday of Advent is sung but without the Alleluia and its verse. The Gloria is not sung, the second collect is Deus, qui de beatae and third for the Church, Ecclesiae. The dismissal is Benedicamus Domino, sung by the Deacon facing the altar.
At ferial Vespers psalms 131, 132, 134, 135 & 136 are sung. The Office hymn is Conditor alme siderum , sung for the last time this year. The antiphon on the Magnificat is the last of the Great 'O's O Emmanuel and is sung, standing, in its entirety both before and after the canticle. The ferial preces are then sung kneeling including the psalm Miserere mei Deus. At Compline the preces are sung kneeling.
In addition to the Office of the day the Little Office of the Blessed Virgin is also sung in the usual manner: Mattins and Lauds before Mattins and Lauds of the day; Prime interpolated into Prime of the day after the chapter, the Hours of the BVM after the Hours of day and Vespers of the BVM before Vespers of the day.