22. The celebration of the Eucharist in a particular Church is of utmost importance.
For the diocesan Bishop, the chief steward of the mysteries of God in the particular Church entrusted to his care, is the moderator, promoter, and guardian of the whole of its liturgical life.[33] In celebrations at which the Bishop presides, and especially in the celebration of the Eucharist led by the Bishop himself with the presbyterate, the deacons, and the people taking part, the mystery of the Church is revealed. For this reason, the solemn celebration of Masses of this sort must be an example for the entire diocese.
The Bishop should therefore be determined that the priests, the deacons, and the lay Christian faithful grasp ever more deeply the genuine meaning of the rites and liturgical texts, and thereby be led to an active and fruitful celebration of the Eucharist. To the same end, he should also be vigilant that the dignity of these celebrations be enhanced. In promoting this dignity, the beauty of the sacred place, of music, and of art should contribute as greatly as possible.
23. Moreover, in order that such a celebration may correspond more fully to the prescriptions and spirit of the sacred Liturgy, and also in order to increase its pastoral effectiveness, certain accommodations and adaptations are specified in this General Instruction and in the Order of Mass.
24. These adaptations consist for the most part in the choice of certain rites or texts, that is, of the chants, readings, prayers, explanations, and gestures which may respond better to the needs, preparation, and culture of the participants and which are entrusted to the priest celebrant., the priest must remember that he is the servant of the sacred Liturgy and that he himself is not permitted, on his own initiative, to add, to remove, or to change anything in the celebration of Mass.
25. In addition, certain adaptations are indicated in the proper place in the Missal and pertain respectively to the diocesan Bishop or to the Conference of Bishops, in accord with the Constitution on the Sacred Liturgy [35] (cf. nos. 387, 388-393).
26. As for variations and the more substantial adaptations in view of the traditions and culture of peoples and regions, to be introduced in accordance with article 40 of the Constitution on the Sacred Liturgy because of benefit or need, the norms set forth in the Instruction on the Roman Liturgy and Inculturation [36] and in nos. 395-399 are to be observed.
From: GENERAL INSTRUCTION OF THE ROMAN MISSAL