Catechism of the Catholic Church
b. Para. 1196: The faithful who celebrate the Liturgy of the Hours are united to Christ our high priest, by the prayer of the Psalms, meditation on the Word of God, and canticles and blessings, in order to be joined with his unceasing and universal prayer that gives glory to the Father and implores the gift of the Holy Spirit on the whole world.
Para. 1174: The mystery of Christ, his Incarnation and Passover, which we celebrate in the Eucharist especially at the Sunday assembly, permeates and transfigures the time of each day, through the celebration of the Liturgy of the Hours, "the divine office" (Cf. SC, ch. IV, 83-101). This celebration, faithful to the apostolic exhortations to "pray constantly," is "so devised that the whole course of the day and night is made holy by the praise of God" (SC 84; 1 Thess 5:17; Eph 6:18). In this "public prayer of the Church" (SC 98), the faithful (clergy, religious, and lay people) exercise the royal priesthood of the baptized. . . .
Para. 1176: The celebration of the Liturgy of the Hours demands not only harmonizing the voice with the praying heart, but also a deeper "understanding of the liturgy and of the Bible, especially of the Psalms" (SC 90).