The Holy Eucharist
The liturgical life of the Church revolves around the sacraments with the Eucharist at the center (National Directory for Catechesis, #35). At Mass, we are fed by the Word and nourished by the Body and Blood of Christ. We believe that the risen Jesus is truly and substantially present in the Eucharist. The Eucharist is not a sign or symbol of Jesus; rather we receive Jesus himself in and through the Eucharist. The priest, through the power of his ordination and the action of the Holy Spirit, transforms the bread and wine into the Body and Blood of Jesus. This is called transubstantiation.
By the consecration the transubstantiation of the bread and wine into the Body and Blood of Christ is brought about. Under the consecrated species of bread and wine of Christ Himself, living and glorious, is present in a true, real and substantial manner: His Body and Blood, with His Soul and Divinity (CCC 1413).