The Holy Sacrifice of the Mass
Our Lord Jesus Christ was once and for all to offer Himself to God the Father by dying on the altar of the Cross, to redeem the world from sin, death, and the power of hell. But because His Priesthood was not to end with His Death, at the Last Supper on the night when He was betrayed, He left His beloved spouse the Church a visible sacrifice by which the one Sacrifice which He was to accomplish on the Cross would be made present sacramentally until the end of the world, and its saving power be applied to the forgiveness of the sins we daily commit.
The risen Christ is truly present in the Holy Eucharist, the Sacrament of His Body and Blood, the perfect fulfillment of His promise
to remain with us until the end of this world.
Recognize in this bread what hung on the Cross, and in this chalice what flowed from His side …
Whatever was in many and varied ways announced beforehand in the sacrifices of the Old Testament
pertains to this one Sacrifice which is revealed in the New Testament.
— St. Augustine of Hippo (354-430)