Reserved sacrament

During the Liturgy of the Eucharist, the second part of the Mass, the elements of bread and wine are considered to have been changed into the veritable Body and Blood of Jesus Christ.

Members of the Orthodox, Anglican, and Lutheran communions also believe that Jesus Christ is really and truly present in the bread and wine, but they believe that the way in which this occurs must forever remain a sacred mystery.

During the Paschal Triduum, the sacrament is taken in procession from the tabernacle, if on the high altar or otherwise in the sanctuary, to the Altar of Repose, and reserved from the end of the Mass of the Lord's Supper until the Communion Rite on Good Friday (called the Mass of the Presanctified, since the Eucharistic Prayer and consecration are omitted in the Good Friday celebration); this period is seen by some as symbolic of the time between the Last Supper and the Crucifixion of Jesus.

In the Apology of Justin Martyr, a 2nd-century Christian writer, he describes the Eucharist ending with the distribution by the deacons to the parishioners "and to those who are absent, they carry away a portion.

Indeed, a Council of Toledo in 480 denounced those who did not immediately consume the sacred species when they received them from the priest at the altar, but at the same time numerous decrees of synods and penalties entered in penitential books impose upon parish priests the duty of reserving the Blessed Sacrament for the use of the sick and dying, and at the same time of keeping it reverently and securely and providing by frequent renewal against any danger of the corruption of the sacred species.

Caskets in the form of a dove or of a tower, made for the most part of one of the precious metals, were commonly used for the purpose, but whether in the early Middle Ages these Eucharistic vessels were kept over the altar, or elsewhere in the church, or in the sacristy, does not clearly appear.

After the 10th century the commonest usage in England and France seems to have been to suspend the Blessed Sacrament in a dove-shaped vessel by a cord over the high altar.

In Germany, in the 14th and 15th centuries, a custom widely prevailed of enshrining the Eucharist in a "sacrament house", often beautifully decorated, separate from the high altar but only a short distance away from it, and on the north or Gospel side of the Church.

This custom seems to have originated in the desire to allow the Blessed Sacrament to be seen by the faithful without exactly contravening the synodal decrees which forbade any continuous exposition.

In the 3rd century, catechumens baptized at Easter or Pentecost might spend eight days in meditation before the Blessed Sacrament, reserved in a home-church, before Christianity was legalized.

Public exposition, formerly permitted only on the feast of Corpus Christi, developed only in recent centuries into a formal service known as Benediction of the Blessed Sacrament.

During the First World War, the practice of reservation was developed in the Anglican church, partly to allow chaplains in the Army to give Communion in the trenches or on the battlefield to severely wounded soldiers.

This pattern, revived in 1955 under Pope Pius XII, was incorporated into the liturgical reforms that followed the Second Vatican Council, but it goes back to the liturgy of Jerusalem, recorded by Egeria in the 4th century.

The fourth reason for reservation is in order that the faithful may receive Communion on a Sunday or other Holy Day in the absence of the priest in the frame of an appropriate service, a need that emerged with the fall in the number of vocations.

The Christian East has no concept of the adoration of the Blessed Sacrament outside of the context of Holy Communion, or of the rite of Benediction which developed in the West after the Great Schism of 1054.