56 The two parts which, in a certain sense, go to make up the Mass, namely, the liturgy of the word and the eucharistic liturgy, are so closely connected with each other that they form but one single act of worship. Accordingly this sacred Synod strongly urges pastors of souls that, when instructing the faithful, they insistently teach them to take their part in the entire Mass, especially on Sundays and feasts of obligation.
Source: Sacrosanctum Concilium (Vatican.va)