At around the time of the Edict of Milan (313 a.d.) and the legalization of Christianity, the question of the inclusion of music in sacred worship was raised and much debated. Did it have a place at all […]? Since the psalms, part of Sacred Scripture, were meant to be sung, […] music was seen as necessarily worthy of being preserved and fostered in the public worship of the Church.
[…] This means that the music proper to the Mass is not merely an addendum to worship, i.e. something external added on to the form and structure of the Mass. Rather, sacred music is an essential element of worship itself. It is an art form which takes its life and purpose from the Sacred Liturgy and is part of its very structure.
The musical tradition of the universal Church is a treasure of inestimable value, greater even than that of any other art. The main reason for this pre-eminence is that, as sacred song united to the words, it forms a necessary or integral part of the solemn liturgy. (Second Vatican Council, Constitution Sacrosanctum Concilium, 112)
This understanding would preclude the common notion that we take the Mass and simply “tack on” four songs (the opening hymn, offertory hymn, communion hymn and recessional hymn), along with the sung ordinary of the Mass (Gloria, Sanctus, etc.) We must come to see that, since sacred music is integral to the Mass, the role of sacred music is to help us sing and pray the texts of the Mass itself, not just ornament it.
(From “Sing to the Lord a New Song” by Abp. Alexander Sample, 2019)