The Eucharist (; also called Holy Communion or the Lord's Supper, among other names) is a Christian rite that is considered a sacrament in most churches, and as an ordinance in others. According to the New Testament, the rite was instituted by Jesus Christ during the Last Supper; giving his disciples bread and wine during the Passover meal, Jesus commanded his followers to "do this in memory of me" while referring to the bread as "my body" and the wine as "my blood". Through the Eucharistic celebration Christians remember both Christ's sacrifice of himself on the cross and his commission of the apostles at the Last Supper.The elements of the Eucharist, sacramental bread (leavened or unleavened) and sacramental wine (or by some grape juice), are consecrated on an altar (or a communion table) and consumed thereafter. Communicants, those who consume the elements, may speak of "receiving the Eucharist", as well as "celebrating the Eucharist". Christians generally recognize a special presence of Christ in this rite, though they differ about exactly how, where, and when Christ is present. While all agree that there is no perceptible change in the elements, Roman Catholics believe that their substances actually become the body and blood of Christ (transubstantiation). Lutherans believe the true body and blood of Christ are really present "in, with, and under" the forms of the bread and wine (sacramental union or, by some, consubstantiation). Reformed Christians believe in a real spiritual presence of Christ in the Eucharist. Others, such as the Plymouth Brethren, take the act to be only a symbolic reenactment of the Last Supper and a memorial. In spite of differences among Christians about various aspects of the Eucharist, there is, according to the Encyclopædia Britannica, "more of a consensus among Christians about the meaning of the Eucharist than would appear from the confessional debates over the sacramental presence, the effects of the Eucharist, and the proper auspices under which it may be celebrated."