The Conception of the BVM is a double feast and the liturgical colour is white. In the 1570 Missale Romanum no texts are given for the feast but a rubric refers to the Nativity of the BVM with a direction to change the word Nativity to Conception. In the 1568 Breviary the user is again referred to the feast of the Nativity but lessons are printed for the first and second nocturns.
At Vespers yesterday afternoon the antiphons Conceptio gloriosae etc were sung with psalms 109, 112, 121, 126 & 147. The chapter was Ab initio et ante saecula and the Office hymn Ave maris stella. The antiphon on the Magnificat was Gloriosae Virginis Mariae Conceptionem etc and the collect Famulis tuis etc. After the collect of the feast commemorations were sung of St. Ambrose and of the Advent feria. At Compline Te lucis was sung with the Doxology Gloria tibi Domine.
At Mattins the invitatory is Conceptionem Virginis Mariae celebremus: Christum ejus Filium adoremus Dominum and the Office hymn is Quem terra pontus aethera. In the first nocturn the antiphons Benedicta tu etc are sung with psalms 8, 18 & 23. The lessons are taken from the twenty-fourth chapter of the Book of Ecclesiasticus beginning at the fifth verse, Ego ex ore Altissimi etc. The first lesson is followed by the responsory Hodie concepta est beata Virgo Maria etc. The lessons are the same as those found in the editions of Clement VIII and Urban VIII. In the second nocturn the antiphons Specie tua etc are sung with psalms 44, 45 & 86. The lessons are from a sermon of St. Ambrose from his Book on Virgins. These are significantly longer than those found in the Clementine (1602) edition of the Breviary. In the third nocturn the antiphons Gaude Maria Virgo etc are sung with psalms 95, 96 & 97. The homily is from St. Jerome on St. Matthew's Gospel. The Te Deum is sung.
At Lauds the antiphons Conceptio gloriosae Virginis Mariae etc are sung with psalms 92, 99, 62-66, Benedicite & 148-149-150. The Office hymn is O gloriosa Domina. The antiphon on the Benedictus is Conceptionem hodiernam etc. After the collect of the feast a commemoration is sung of the Advent feria.
At Prime and the Hours the antiphons Conceptio gloriosae Virginis Mariae etc are sung with the festal psalms. The hymns have the Doxology Gloria tibi Domine etc. At Prime the versicle in the short responsory is changed to Qui natus es de Virgine and the lectio brevis is In plateis.
Mass is sung after Terce. The Mass formula is Salve sancta parens. The Gloria is sung, the second collect is of the Advent feria. The Creed is sung and the preface is of the BVM.
At Vespers the antiphons Conceptio gloriosae Virginis Mariae are sung with the psalms of the BVM. The hymn is Ave maris stella. After the collect of the feast a commemoration is sung of the Advent feria.