General Instruction of the Roman Missal: Chapter IV, The Different Forms of Celebrating Mass
145After the prayer In spiritu humilitatis (Lord God, we ask you to receive us) or after the incensation, the priest washes his hands standing at the side of the altar and, as the minister pours the water, says quietly, Lava me, Domine (Lord, wash away my iniquity).
146Upon returning to the middle of the altar, the priest, facing the people and extending and then joining his hands, invites the people to pray, saying, Orate, fratres (Pray, brethren). The people rise and make their response: Suscipiat Dominus (May the Lord accept). Then the priest, with hands extended, says the prayer over the offerings. At the end the people make the acclamation, Amen.
147Then the priest begins the Eucharistic Prayer. In accordance with the rubrics (cf. no. 365), he selects a Eucharistic Prayer from those found in The Roman Missal or approved by the Apostolic See. The Eucharistic Prayer demands, by its very nature, that only the priest say it in virtue of his ordination. The people, for their part, should associate themselves with the priest in faith and in silence, as well as through their parts as prescribed in the course of the Eucharistic Prayer: namely, the responses in the Preface dialogue, the Sanctus, the acclamation after the consecration, the acclamatory Amen after the final doxology, as well as other acclamations approved by the Conference of Bishops and recognized by the Holy See.
It is very appropriate that the priest sing those parts of the Eucharistic Prayer for which musical notation is provided.
148As he begins the Eucharistic Prayer, the priest extends his hands and sings or says, Dominus vobiscum (The Lord be with you). The people respond, Et cum spiritu tuo (And also with you). As he continues, Sursum corda (Lift up your hearts), he raises his hands. The people respond, Habemus ad Dominum (We lift them up to the Lord). Then the priest, with hands outstretched, adds, Gratias agamus Domino Deo nostro (Let us give thanks to the Lord, our God), and the people respond, Dignum et iustum est (It is right to give him thanks and praise). Next, the priest, with hands extended, continues the Preface. At its conclusion, he joins his hands and, together with everyone present, sings or says aloud the Sanctus (cf. no. 79b).
149The priest continues the Eucharistic Prayer in accordance with the rubrics that are set forth in each of the Prayers.
If the celebrant is a Bishop, in the Prayers, after the words Papa nostro N. (N., our Pope), he adds, et me, indigno famulo tuo (and me, your unworthy servant). If, however, the Bishop is celebrating outside his own diocese, after the words Papa nostro N. (N., our Pope), he adds, et me indigno famulo tuo, et fratre meo N., Episcopo huius Ecclesiae N. (me, your unworthy servant, and my brother N., the Bishop of this Church of N.).
The diocesan Bishop or anyone equivalent to him in law must be mentioned by means of this formula: una cum famulo tuo Papa nostro N. et Episcopo (or Vicario, Prelato, Praefecto, Abbate) (together with your servant N., our Pope, and N., our Bishop [or Vicar, Prelate, Prefect, Abbot]).
It is permitted to mention Coadjutor and Auxiliary Bishops in the Eucharistic Prayer, but not other Bishops who happen to be present. When several are to be named, this is done with the collective formula et Episcopo nostro N. eiusque Episcopis adiutoribus (N., our Bishop and his assistant Bishops).
In each of the Eucharistic Prayers, these formulas are to be modified according to the requirements of grammar.
150A little before the consecration, when appropriate, a server rings a bell as a signal to the faithful. According to local custom, the server also rings the bell as the priest shows the host and then the chalice.
If incense is used, a server incenses the host and the chalice when each is shown to the people after the consecration.
151After the consecration when the priest has said, Mysterium fidei (Let us proclaim the mystery of faith), the people sing or say an acclamation using one of the prescribed formulas.
At the end of the Eucharistic Prayer, the priest takes the paten with the host and the chalice and elevates them both while alone singing or saying the doxology, Per ipsum (Through him). At the end the people make the acclamation, Amen. Then the priest places the paten and the chalice on the corporal.
152After the Eucharistic Prayer is concluded, the priest, with hands joined, says the introduction to the Lord’s Prayer. With hands extended, he then says this prayer together with the people.
153After the Lord’s Prayer is concluded, the priest alone, with hands extended, says the embolism Libera nos (Deliver us). At the end, the people make the acclamation, Quia tuum est regnum (For the kingdom).
154Then the priest, with hands extended, says aloud the prayer, Domine Iesu Christe, qui dixisti (Lord Jesus Christ, you said). After this prayer is concluded, extending and then joining his hands, he gives the greeting of peace while facing the people and saying, Pax Domini sit semper vobiscum (The peace of the Lord be with you always). The people answer, Et cum spiritu tuo (And also with you). Afterwards, when appropriate, the priest adds, Offerte vobis pacem (Let us offer each other the sign of peace).
The priest may give the sign of peace to the ministers but always remains within the sanctuary, so as not to disturb the celebration. In the dioceses of the United States of America, for a good reason, on special occasions (for example, in the case of a funeral, a wedding, or when civic leaders are present) the priest may offer the sign of peace to a few of the faithful near the sanctuary. At the same time, in accord with the decisions of the Conference of Bishops, all offer one another a sign that expresses peace, communion, and charity. While the sign of peace is being given, one may say, Pax Domini sit semper tecum (The peace of the Lord be with you always), to which the response is Amen.
155The priest then takes the host and breaks it over the paten. He places a small piece in the chalice, saying quietly, Haec commixtio (May this mingling). Meanwhile the Agnus Dei is sung or said by the choir and congregation (cf. no. 83).
156Then the priest, with hands joined, quietly says the preparatory prayer of Communion: Domine Iesu Christe, Fili Dei vivi (Lord Jesus Christ, Son of the living God) or Perceptio Corporis et Sanguinis (Lord Jesus Christ, with faith in your love and mercy).
157When the prayer is concluded, the priest genuflects, takes the host consecrated in the same Mass, and, holding it slightly raised above the paten or above the chalice, while facing the people, says, Ecce Agnus Dei (This is the Lamb of God). With the people he adds, Domine, non sum dignus (Lord, I am not worthy).
158After this, standing and turned toward the altar, the priest says quietly, Corpus Christi custodiat me in vitam aeternam (May the Body of Christ bring me to everlasting life) and reverently receives the Body of Christ. Then he takes the chalice, saying quietly, Sanguis Christi custodiat me in vitam aeternam (May the Blood of Christ bring me to everlasting life), and reverently receives the Blood of Christ.
159The Communion chant begins while the priest is receiving the Sacrament (cf. no. 86).
160The priest then takes the paten or ciborium and goes to the communicants, who, as a rule, approach in a procession.
The faithful are not permitted to take the consecrated bread or the sacred chalice by themselves and, still less, to hand them from one to another. The norm for reception of Holy Communion in the dioceses of the United States is standing. Communicants should not be denied Holy Communion because they kneel. Rather, such instances should be addressed pastorally, by providing the faithful with proper catechesis on the reasons for this norm.
When receiving Holy Communion, the communicant bows his or her head before the Sacrament as a gesture of reverence and receives the Body of the Lord from the minister. The consecrated host may be received either on the tongue or in the hand, at the discretion of each communicant. When Holy Communion is received under both kinds, the sign of reverence is also made before receiving the Precious Blood.
161If Communion is given only under the species of bread, the priest raises the host slightly and shows it to each, saying, Corpus Christi (The Body of Christ). The communicant replies, Amen, and receives the Sacrament either on the tongue or, where this is allowed and if the communicant so chooses, in the hand. As soon as the communicant receives the host, he or she consumes it entirely.
If, however, Communion is given under both kinds, the rite prescribed in nos. 284-287 is followed.
162The priest may be assisted in the distribution of Communion by other priests who happen to be present. If such priests are not present and there is a very large number of communicants, the priest may call upon extraordinary ministers to assist him, i.e., duly instituted acolytes or even other faithful who have been deputed for this purpose.[97] In case of necessity, the priest may depute suitable faithful for this single occasion.[98]
These ministers should not approach the altar before the priest has received Communion, and they are always to receive from the hands of the priest celebrant the vessel containing either species of the Most Holy Eucharist for distribution to the faithful.
163When the distribution of Communion is finished, the priest himself immediately and completely consumes at the altar any consecrated wine that happens to remain; as for any consecrated hosts that are left, he either consumes them at the altar or carries them to the place designated for the reservation of the Eucharist.
Upon returning to the altar, the priest collects any fragments that may remain. Then, standing at the altar or at the credence table, he purifies the paten or ciborium over the chalice, then purifies the chalice, saying quietly, Quod ore sumpsimus (Lord, may I receive), and dries the chalice with a purificator. If the vessels are purified at the altar, they are carried to the credence table by a minister. Nevertheless, it is also permitted, especially if there are several vessels to be purified, to leave them suitably covered on a corporal, either at the altar or at the credence table, and to purify them immediately after Mass following the dismissal of the people.
164Afterwards, the priest may return to the chair. A sacred silence may now be observed for some period of time, or a Psalm or another canticle of praise or a hymn may be sung (cf. no. 88).
165Then, standing at the chair or at the altar and facing the people the priest, with hands joined says, Oremus (Let us pray); then, with hands extended, he recites the prayer after Communion. A brief period of silence may precede the prayer, unless this has been already observed immediately after Communion. At the end of the prayer the people say the acclamation, Amen.
166When the prayer after Communion is concluded, brief announcements to the people may be made, if they are needed.
167Then the priest, extending his hands, greets the people, saying, Dominus vobiscum (The Lord be with you). They answer, Et cum spiritu tuo (And also with you). The priest, joining his hands again and then immediately placing his left hand on his breast, raises his right hand and adds, Benedicat vos omnipotens Deus (May Almighty God bless you) and, as he makes the Sign of the Cross over the people, continues, Pater, et Filius, et Spiritus Sanctus (the Father, and the Son, and the Holy Spirit). All answer, Amen.
On certain days and occasions this blessing, in accordance with the rubrics, is expanded and expressed by a prayer over the People or another more solemn formula.