§1364
Sacraments › … › V. The Sacramental Sacrifice Thanksgiving, Memorial, Presence
The sacrificial memorial of Christ and of his Body, the Church
In the New Testament, the memorial takes on new meaning. When the Church celebrates the Eucharist, she commemorates Christ's Passover, and it is made present the sacrifice Christ offered once for all on the cross remains ever present. "As often as the sacrifice of the Cross by which 'Christ our Pasch has been sacrificed' is celebrated on the altar, the work of our redemption is carried out."
Source: Catechism of the Catholic Church (Vatican.va)