Feast of the Corpus Christi
Lord Jesus Christ, You gave us the Eucharist as the memorial of Your suffering and death. May our worship of this sacrament of Your Body and Blood help us to experience the salvation You won for us and the peace of the kingdom where you live with the Father and the Holy Spirit, one God, for ever and ever. Amen.
The Catechism of the Catholic Church on the Eucharist
1324 The Eucharist is "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."
Below is the Pange Lingua, written by St. Thomas Aquinas, who was given the task of composing hymns for the celebration of Corpus Christi, by Pope Urban IV. The better known Tantum Ergo (Down in adoration falling) actually forms the last two verses of the Pange Lingua.