17. In the manner and order of performing the solemnities of the Mass on that very day [Christmas] and on all important festivals is to be as follows. The priests and deacons, when the hour draws near for them to begin the Mass enter the sacristy, clothe themselves with the proper vestments for the Mass, and arrange themselves according to rank, as is the custom.
18. And then the clergy begins the antiphon proper to that day.
19. When they commence the first verse of the psalm, the priests leave the sacristy according to the date of their ordination, first those priests who are celebrating the public Mass on that day, walking together two by two.
|25. Then he approaches the altar and, with his entire body prostrate upon the floor, he pours our prayers for himself and for the sins of the people, until they sing the introit antiphon with the psalm and the Gloria patri with the verses ad repentendum.|
26. Arising from prayer he kisses the holy gospel book that is placed on the altar, he and all the deacons as well.
27. He moves behind the altar with his deacons and looks out from the East [toward the congregation] while the deacons remain next to him, one group on the right and the other on the left, the other priests stand next to the altar, arranged by their rank.
28. When the Introit antiphon and the ninefold Kyrie eleison are completed, the priest, facing the people, begins the Gloria in excelsis Deo. And when they arrive at the words pax hominibus bonae voluntatis they look again toward the East until the Gloria in excelsis Deo is completed.
29. And then the priest turns to the people and says, "Peace to you," and all respond, "And with your spirit."
42. Then the priest goes to the altar and takes the proper offerings; he raises his eyes to heaven and his hands with the offerings, and prays to the Lord, then places the offerings on the altar.
43. Similarly he offers the wine.
44. The deacons go behind the priest and arrange themselves by rank, and the subdeacons go behind the altar and place themselves by rank, while the priests stand in order before the altar.
45. Then the celebrating priest, with the other priests on his right and left, offers a prayer.
46. He inclines his face to the earth and says the prayer in secret, with no one else able to hear it, until he arrives at the words: "through all ages of ages," and all reply, "Amen."
47. Immediately he says, "The Lord be with you," then "Lift up your hearts," then "Let us give thanks to the Lord our God," and then he commences the preface; he lifts his voice and proclaims the preface so that it may be heard by virtually all.