Catechism of the Catholic Church
1117 As she has done for the canon of Sacred Scripture and for the doctrine of the faith, the Church, by the power of the Spirit who guides her "into all truth," has gradually recognized this treasure received from Christ and, as the faithful steward of God's mysteries, has determined its "dispensation." 34 Thus the Church has discerned over the centuries that among liturgical celebrations there are seven that are, in the strict sense of the term, sacraments instituted by the Lord.
1118 The sacraments are "of the Church" in the double sense that they are "by her" and "for her." They are "by the Church," for she is the sacrament of Christ's action at work in her through the mission of the Holy Spirit. They are "for the Church" in the sense that "the sacraments make the Church," 35 since they manifest and communicate to men, above all in the Eucharist, the mystery of communion with the God who is love, One in three persons.
1119 Forming "as it were, one mystical person" with Christ the head, the Church acts in the sacraments as "an organically structured priestly community." 36 Through Baptism and Confirmation the pRiestly people is enabled to celebrate the liturgy, while those of the faithful "who have received Holy Orders, are appointed to nourish the Church with the word and grace of God in the name of Christ." 37
1120 The ordained ministry or ministerial priesthood is at the service of the baptismal priesthood. 38 The ordained priesthood guarantees that it really is Christ who acts in the sacraments through the Holy Spirit for the Church. The saving mission entrusted by the Father to his incarnate Son was committed to the apostles and through them to their successors: they receive the Spirit of Jesus to act in his name and in his person. 39 The ordained minister is the sacramental bond that ties the liturgical action to what the apostles said and did and, through them, to the words and actions of Christ, the source and foundation of the sacraments.
1121 The three sacraments of Baptism, Confirmation, and Holy Orders confer, in addition to grace, a sacramental character or "seal" by which the Christian shares in Christ's priesthood and is made a member of the Church according to different states and functions. This configuration to Christ and to the Church, brought about by the Spirit, is indelible, 40 it remains for ever in the Christian as a positive disposition for grace, a promise and guarantee of divine protection, and as a vocation to divine worship and to the service of the Church. Therefore these sacraments can never be repeated.
English Translation of the Cathechism of the Catholic Church for the United States of America © 1997, United States Catholic Conference, Inc.