Only priests can preside at the sacrament in which bread and wine are transformed into Christ's body and blood?

• That's why consecrating the Eucharist may be a priest's most important function. The Eucharist is the ritual sacrament involving bread and wine that celebrates Christ's Last Supper with his apostles. Also known as Communion, the Eucharist represents the sacrifice of Christ's death and is considered the center of Catholic existence. It is celebrated at Mass.

• Some Christian denominations consider the Eucharist a symbolic ritual, in which the bread and wine represent Christ's body and blood. But Roman Catholics believe the bread and wine actually become the body and blood of Christ. The belief is based on strict adherence to Christ's words at the Last Supper, as described in the Gospels: "Take ye and eat. This is my body, which shall be delivered for you."

• Because the Last Supper was a traditional Passover meal, the Catholic ritual calls for unleavened bread and fermented red wine.

• Ignatius of Antioch described the Eucharist as "the antidote we take in order not to die but to live forever in Jesus Christ."