As explained in greater detail in the Catechism of the Catholic Church (CCC), the liturgy is something that "the whole Christ", Head and Body, celebrates — Christ, the one High Priest, together with his Body, the Church in heaven and on earth. Involved in the heavenly liturgy are the angels and the saints of the Old Covenant and the New, in particular Mary, the Mother of God, the Apostles, the Martyrs and "a great multitude, which no man could number, out of every nation and of all tribes and peoples and tongues" (Revelation 7:9). The Church on earth, "a royal priesthood" (1 Peter 2:9), celebrates the liturgy in union with these: the baptized offering themselves as a spiritual sacrifice, the ordained ministers celebrating at the service of all the members of the Church in accordance with the order received, and bishops and priests acting in the person of Christ.
In the Church’s liturgy the divine blessing is fully revealed and communicated. The Father is acknowledged and adored as the source and the end of all the blessings of creation and salvation. In his Word who became incarnate, died, and rose for us, he fills us with his blessings. Through his Word, he pours into our hearts the Gift that contains all gifts, the Holy Spirit. (CCC, 1082)