90 The divine office, because it is the public prayer of the Church, is a source of piety, and nourishment for personal prayer. And therefore priests and all others who take part in the divine office are earnestly exhorted in the Lord to attune their minds to their voices when praying it. The better to achieve this, let them take steps to improve their understanding of the liturgy and of the bible, especially of the psalms. In revising the Roman office, its ancient and venerable treasures are to be so adapted that all those to whom they are handed on may more extensively and easily draw profit from them.
Source: Sacrosanctum Concilium (Vatican.va)