Mediator Dei reminds us of the texts of the prayers of the Ordinary and what is now Eucharistic Prayer I: it’s not the royal “we.”
87. Moreover, the rites and prayers of the eucharistic sacrifice signify and show no less clearly that the oblation of the Victim is made by the priests in company with the people. For not only does the sacred minister, after the oblation of the bread and wine when he turns to the people, say the significant prayer: “Pray brethren, that my sacrifice and yours may be acceptable to God the Father Almighty;”[Roman Missal, Ordinary of the Mass] but also the prayers by which the divine Victim is offered to God are generally expressed in the plural number: and in these it is indicated more than once that the people also participate in this august sacrifice inasmuch as they offer the same. The following words, for example, are used: “For whom we offer, or who offer up to Thee . . . We therefore beseech thee, O Lord, to be appeased and to receive this offering of our bounded duty, as also of thy whole household. . . We thy servants, as also thy whole people . . . do offer unto thy most excellent majesty, of thine own gifts bestowed upon us, a pure victim, a holy victim, a spotless victim.”[Roman Missal, Canon of the Mass]
The priesthood of baptism:
88. Nor is it to be wondered at, that the faithful should be raised to this dignity. By the waters of baptism, as by common right, Christians are made members of the Mystical Body of Christ the Priest, and by the “character” which is imprinted on their souls, they are appointed to give worship to God. Thus they participate, according to their condition, in the priesthood of Christ.
Catholic Sensibility 