IV. Holy Thursday Evening Mass of the Lord's Supper
44. With the celebration of Mass on the evening of Holy Thursday, "the
Church begins the Easter Triduum and recalls the Last Supper in which the Lord
Jesus, on the night he was betrayed, showing his love for those who were his own
in the world, he gave his body and blood under the species of bread and wine
offering to his Father and giving them to the Apostles so that they might
partake of them, and he commanded them and their successors in the priesthood to
perpetuate this offering." 
45. Careful attention should be given to the mysteries that are commemorated
in this Mass: the institution of the Eucharist, the institution of the
priesthood, and Christ's command of brotherly love; the homily should explain
46. The Mass of the Lord's Supper is celebrated in the evening, at a time
that is more convenient for the full participation of the whole local community.
All priests may concelebrate, even if on this day they have already
concelebrated the Chrism Mass or if, for the good of the faithful, they must
celebrate another Mass. 
47. Where pastoral considerations require it, the local ordinary may permit
another Mass to be celebrated in churches and oratories in the evening and, in
the case of true necessity, even in the morning, but only for those faithful
who cannot otherwise participate in the evening Mass. Care should nevertheless
be taken to ensure that celebrations of this kind do not take place for the
benefit of private persons or of small groups, and that they are not to the
detriment of the main Mass.
According to the ancient tradition of the Church, all Masses without the
participation of the people are forbidden on this day. 
48. The tabernacle should be completely empty before the celebration.
 Hosts for the communion of the faithful
should be consecrated during that celebration. A sufficient amount of bread
should be consecrated to provide also for communion the following day.
49. For the reservation of the Blessed Sacrament, a place should be
prepared and adorned in such a way as to be conducive to prayer and meditation;
that sobriety appropriate to the liturgy of these days is enjoined, to the
avoidance or suppression of all abuses. 
When the tabernacle is in a chapel separated from the central part of the
church, it is appropriate to prepare the place of repose and adoration there.
50. During the singing of the hymn "Gloria in excelsis," in
accordance with local custom, the bells may be rung but should thereafter remain
silent until the "Gloria in excelsis" of the Easter Vigil,
unless the conference of bishops or the local ordinary, for a suitable reason,
has decided otherwise.  During the same
period, the organ and other musical instruments may be used only for the purpose
of supporting the singing. 
51. The washing of the feet of chosen men which, according to tradition, is
performed on this day, represents the service and charity of Christ, who came
"not to be served, but to serve." 
This tradition should be maintained, and its proper significance explained.
52. Gifts for the poor, especially those collected during Lent as the fruit
of penance, may be presented in the offertory procession while the people sing
"Ubi caritas est vera." 
53. It is more appropriate that the Eucharist be borne directly from the
altar by the deacons or acolytes, or extraordinary ministers, at the moment of
communion for the sick and infirm who must communicate at home, so that, in
this way, they may be more closely united to the celebrating Church.
54. After the postcommunion prayer, the procession forms with the crossbearer
at its head. The Blessed Sacrament, accompanied by lighted candles and incense,
is carried through the church to the place of reservation, to the singing of the
hymn "Pange lingua" or some other eucharistic song.
 This rite of transfer of the Blessed
Sacrament may not be carried out if the liturgy of the Lord's passion will not
be celebrated in that same church on the following day. 
55. The Blessed Sacrament should be reserved in a closed tabernacle or pyx.
Under no circumstances may it be exposed in a monstrance.
The place where the tabernacle or pyx is situated must not be made to
resemble a tomb, and the expression tomb is to be avoided: for the chapel
of repose is not prepared so as to represent the Lord's burial but for
the custody of the eucharistic bread that will be distributed in communion on
56. After the Mass of the Lord's Supper, the faithful should be encouraged to
spend a suitable period of time during the night in the church in adoration
before the Blessed Sacrament that has been solemnly reserved. Where appropriate,
this prolonged eucharistic adoration may be accompanied by the reading of some
part of the gospel of Saint John (ch. 13-17).
From midnight onward, however, the adoration should be made without external
solemnity, for the day of the Lord's passion has begun. 
57. After Mass, the altar should be stripped. It is fitting that any crosses
in the church be covered with a red or purple veil, unless they have already
been veiled on the Saturday before the fifth Sunday of Lent. Lamps should not be
lit before the images of saints.