Holy Thursday is the most complex and profound of all religious observances, saving only the Easter Vigil. It celebrates both the institution by Christ himself of the Eucharist and of the institution of the sacerdotal priesthood (as distinct from the"priesthood of all believers") for in this, His last supper with the disciples, a celebration of Passover, He is the self-offered Passover Victim, and every ordained priest to this day presents this same sacrifice, by Christ's authority and command, in exactly the same way. The Last Supper was also Christ's farewell to His assembled disciples, some of whom would betray, desert or deny Him before the sun rose again.
Around the world, bishops and priests come together at their local Cathedrals on Holy Thursday morning to celebrate the institution of the priesthood. During the Mass, the bishop blesses the Oil of Chrism that will be used for Baptism, Confirmation, and Anointing of the sick or dying.
At this Mass, the bishop washes the feet of twelve priests to symbolise Christ’s washing of his twelve Apostles, our first bishops and priests.
Later that night, after sundown – because Passover began at sundown – the Holy Thursday Liturgy takes place, marking the end of Lent and the beginning of the sacred "Triduum,” or three, of Holy Week. These days are the three holiest days in the Catholic Church.
This Mass stresses the importance Jesus puts on the humility of service, and the need for cleansing with water, a symbol of baptism. Also emphasised is the critical importance of the Eucharist and the sacrifice of Christ’s Body, which we now find present in the consecrated Host.
At the conclusion of the Mass, the faithful are invited to continue Adoration of the Blessed Sacrament throughout the night, just as the disciples were invited to stay up with the Lord during His agony in the garden before His betrayal by Judas.
After Holy Thursday, no Mass will be celebrated again in the Church until the Easter Vigil celebrates and proclaims the Resurrection of the Lord Jesus Christ.