84 By tradition going back to early Christian times, the divine office is devised so that the whole course of the day and night is made holy by the praises of God. Therefore, when this wonderful song of praise is rightly performed by priests and others who are deputed for this purpose by the Church's ordinance, or by the faithful praying together with the priest in the approved form, then it is truly the voice of the bride addressed to her bridegroom; It is the very prayer which Christ Himself, together with His body, addresses to the Father.
Source: Sacrosanctum Concilium (Vatican.va)