II Celebration on Sundays and Weekdays
25. The Celebration of the Eucharist on Sundays
In order that the faithful may willingly fulfill the precept to sanctify this day and understand why the Church calls them together to celebrate the Eucharist every Sunday, from the very outset of their Christian formation "Sunday should be presented to them as the primordial feast day,"76 on which, assembled together, they are to hear the Word of God and take part in the Paschal Mystery.
It is important that the active participation of the entire people in the Sunday celebration, which is expressed in singing, should be assiduously promoted. In fact, sung Masses (<Missae in cantu>) should be preferred as far as possible.79
On Sundays and feast days above all, the celebrations which take place in other churches or oratories should be arranged in connection with the celebrations in the parish church so that they contribute to the general pastoral effort. It is preferable that small religious non-clerical communities and other similar communities, especially those that work in the parish, should take part in the parish Mass on these days.