The Christian faithful who gather together as one to await the Lord’s coming are instructed by the Apostle Paul to sing together psalms, hymns, and spiritual songs (cf. Col 3:16). Singing is the sign of the heart’s joy (cf. Acts 2:46). Thus St. Augustine says rightly, “Singing is for one who loves.” There is also the ancient proverb: “One who sings well prays twice.”
Great importance should therefore be attached to the use of singing in the celebration of the Mass, with due consideration for the culture of the people and abilities of each liturgical assembly. Since faithful from different countries come together ever more frequently, it is fitting that they know how to sing together at least some parts of the Ordinary of the Mass in Latin, especially the Creed and the Lord’s Prayer, set to the simpler melodies. (GIRM 39-41)
"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 preminence is that, as a combination of sacred music and words, it forms a necessary or integral part of solemn liturgy." The composition and singing of inspired psalms, often accompanied by musical instruments, were already closely linked to the liturgical celebrations of the Old Covenant. The Church continues and develops this tradition: "Address . . . one another in psalms and hymns and spiritual songs, singing and making melody to the Lord with all your heart." "He who sings prays twice."
Song and music fulfill their function as signs according to three principal criteria: beauty expressive of prayer, the unanimous participation of the assembly at the designated moments, and the solemn character of the celebration. In this way they participate in the purpose of the liturgical words and actions: the glory of God and the sanctification of the faithful:
- How I wept, deeply moved by your hymns, songs, and the voices that echoed through your Church! What emotion I experienced in them! Those sounds flowed into my ears distilling the truth in my heart. A feeling of devotion surged within me, and tears streamed down my face - tears that did me good. (St. Augustine, Conf. 9,6,14:PL 32,769-770)
The harmony of signs (song, music, words, and actions) is all the more expressive and fruitful when expressed in the cultural richness of the People of God who celebrate. Hence "religious singing by the faithful is to be intelligently fostered so that in devotions and sacred exercises as well as in liturgical services," in conformity with the Church's norms, "the voices of the faithful may be heard." (Catechism of the Catholic Church #1156-1158)