Every legitimate celebration of the Eucharist is directed by the Bishop, either in person or through priests who are his helpers.78Cf. Second Vatican Ecumenical Council, Dogmatic Constitution on the Church, Lumen gentium, nos. 26, 28; Constitution on the Sacred Liturgy, Sacrosanctum Concilium, no. 42. Whenever the Bishop is present at a Mass where the people are gathered, it is most fitting that he himself celebrate the Eucharist and associate priests with himself as concelebrants in the sacred action. This is done not to add external solemnity to the rite, but to express in a clearer light the mystery of the Church, “the sacrament of unity.”79Cf. Second Vatican Ecumenical Council, Constitution on the Sacred Liturgy, Sacrosanctum Concilium, no. 26. Even if the Bishop does not celebrate the Eucharist but has assigned someone else to do this, it is appropriate that he should preside over the Liturgy of the Word, wearing the pectoral cross, stole, and cope over an alb, and that he give the blessing at the end of Mass.80Cf. Caeremoniale Episcoporum, editio typica, 1984, nos. 175-186.
A priest also, who possesses within the Church the power of Holy Orders to offer sacrifice in the person of Christ,81Cf. Second Vatican Ecumenical Council, Dogmatic Constitution on the Church, Lumen gentium, no. 28; Decree on the Ministry and Life of Priests, Presbyterorum ordinis, no. 2. stands for this reason at the head of the faithful people gathered together here and now, presides over their prayer, proclaims the message of salvation to them, associates the people with himself in the offering of sacrifice through Christ in the Holy Spirit to God the Father, gives his brothers and sisters the Bread of eternal life, and partakes of it with them. When he celebrates the Eucharist, therefore, he must serve God and the people with dignity and humility, and by his bearing and by the way he says the divine words he must convey to the faithful the living presence of Christ.
After the priest, the deacon, in virtue of the sacred ordination he has received, holds first place among those who minister in the Eucharistic Celebration. For the sacred Order of the diaconate has been held in high honor in the Church even from the time of the Apostles.82Cf. Paul VI, Apostolic Letter Sacrum diaconatus ordinem, 18 June 1967: AAS 59 (1967), pp. 697-704; The Roman Pontifical, Rites of Ordination of a Bishop, of Priests, and of Deacons, editio typica altera, 1989, no. 173. At Mass the deacon has his own part in proclaiming the Gospel, in preaching God’s word from time to time, in announcing the intentions of the Prayer of the Faithful, in ministering to the priest, in preparing the altar and serving the celebration of the Sacrifice, in distributing the Eucharist to the faithful, especially under the species of wine, and sometimes in giving directions regarding the people’s gestures and posture.