"And it happened that, while he was with them at table, he took bread, said the blessing, broke it, and gave it to them. With that their eyes were opened and they recognized him, but he vanished from their sight."
Luke 24:30-31

1324 The Eucharist is "the source and summit of the Christian life."  "The other sacraments, and indeed all ecclesiastical ministries and works of the apostolate, are bound up with the Eucharist and are oriented toward it. For in the blessed Eucharist is contained the whole spiritual good of the Church, namely Christ himself, our Pasch." 

1325 "The Eucharist is the efficacious sign and sublime cause of that communion in the divine life and that unity of the People of God by which the Church is kept in being. It is the culmination both of God's action sanctifying the world in Christ and of the worship men offer to Christ and through him to the Father in the Holy Spirit." 

1326 Finally, by the Eucharistic celebration we already unite ourselves with the heavenly liturgy and anticipate eternal life, when God will be all in all. 

1327 In brief, the Eucharist is the sum and summary of our faith: "Our way of thinking is attuned to the Eucharist, and the Eucharist in turn confirms our way of thinking."

1331  [We call it] Holy Communion, because by this sacrament we unite ourselves to Christ, who makes us sharers in his Body and Blood to form a single body.

1337 The Lord, having loved those who were his own, loved them to the end... In order to leave them a pledge of this love, in order never to depart from his own and to make them sharers in his Passover, he instituted the Eucharist as the memorial of his death and Resurrection, and commanded his apostles to celebrate it until his return; "thereby he constituted them priests of the New Testament."