Taken from the Encyclical Letter on the Eucharist - Pope John Paul II
Because even when it is celebrated on the humble altar of a country church, the Eucharist is always in some way celebrated on the altar of the world. It unites heaven and earth. It embraces and permeates all creation. The Son of God became man in order to restore all creation, in one supreme act of praise, to the One who made it from nothing. He, the Eternal High Priest who by the blood of His Cross entered the eternal sanctuary, thus gives back to the Creator and Father all creation redeemed. He does so through the priestly ministry of the Church, to the glory of the Most Holy Trinity. Truly this is the mysterium fidei which is accomplished in the Eucharist: the world which came forth from the hands of God the Creator now returns to Him redeemed by Christ.