The Sacraments are the actions of Christ in the Church, the primordial sacrament

The Church always enjoys Christ’s presence and ministers to him; the mystery of Christ continues in the Church, specifically through those signs instituted by Christ which signify and produce the gift of grace and which are known as sacraments (see Council of Trent, Decree on the Sacraments, DS 1601).

Since the Church is not merely the people of God but also, as it were, in Christ ‘a sign and instrument ... of communion with God and of unity among all men’ (LG 1) it should be regarded as the primordial sacrament.

The sacraments are the primary and fundamental actions by which Jesus Christ constantly bestows his Spirit on the faithful, making them a holy people who, in him and with him, offer themselves as an acceptable offering to the Father. The sacraments are surely to be regarded as being of inestimable value to the Church, to which belongs the power to administer them. They must always however be referred to Christ, from whom their effectiveness derives. In fact, it is Christ who baptizes. It is not so much a man who celebrates the Eucharist, as Christ himself: he offers himself by the ministry of priests in the sacrifice of the Mass, (DS 1743). The sacramental action is, first and foremost, Christ’s action and the Church’s ministers are, as it were, his instruments.