Maundy Thursday begins the Sacred Triduum (Latin = three days), which from the 4th century celebrated the Paschal Mystery. Originally these three days began on Good Friday.
It was natural, however, to include Maundy Thursday because Good Friday was reckoned from sunset on the previous evening. The oldest and still official name of this day is Thursday of the Lord's Supper. It commemorates the historical Gospel events surrounding the Last Supper and the institution of the Holy Eucharist. "Maundy" Thursday comes from the solemn ritual of washing the feet in imitation of Jesus at his Last Supper. The title is a corruption of mandatum (Latin = commandment), from the words of Jesus: "A new commandment I give you..." (John 13:34)
The Maundy Thursday ritual has included a ceremonial washing of feet by the presiding celebrant since the 5th century in some local churches, since the late 7th century in Spain and Gaul, and the 12th in Rome. This ritual imitates Jesus' action of humility and service. Appropriate hymns are sung during this symbolic washing. Twelve participants are chosen at large from parishioners. Some parishes deliberately invite "twelve apostles" from very poor or neglected citizens in the community to emphasize the theme.
At the end of the Maundy Thursday liturgy, consecrated Bread and Wine are carried in procession to an altar of reservation, to be used in the Liturgy of Good Friday. The pervading mood is an atmosphere of quiet waiting with the Lord.
The first hints of a new theme quickly become obvious, however: an anticipation of Christ's suffering and death. The altar table, symbolic of Christ, is completely stripped, and many of the surrounding articles in the church sanctuary are removed. The service concludes in reverent silence.