Papal remarks on the importance of music in the Liturgy
“I desire, in accordance with the request advanced by the Synod Fathers, that Gregorian chant be suitably esteemed and employed as the chant proper to the Roman liturgy”— Sacramentum Caritatis§4
"An authentic updating of sacred music can take place only in the lineage of the great tradition of the past, of Gregorian chant and sacred polyphony." [Speaking in the Sistine Chapel following a tribute concert to Dominico Bartolucci, June 24, 2006.]
Not every kind of music can have a place in Christian worship. It has its standards, and that standard is the Logos. If we want to know whom we are dealing with, the Holy Spirit or the unholy spirit, we have to remember that it is the Holy Spirit who moves us to say, “Jesus is Lord” (~Cor 12:3). The Holy Spirit leads us to the Logos, and he leads us to a music that serves the Logos as a sign of the sursum corda, the lifting up of the human heart. Does it integrate man by drawing him to what is above, or does it cause his disintegration into formless intoxication or mere sensuality? That is the criterion for a music in harmony with logos, a form of thatlogike latreia (reasonable, logos-worthy worship)… [The Spirit of the Liturgy, (SF, CA: Ignatius, 2000), p. 151]
...more on Pope Benedict and Sacred Music
Venerable Pope John Paul II
“Liturgical music must meet the specific prerequisites of the Liturgy: full adherence to the text it presents, synchronization with the time and moment in the Liturgy for which it is intended, appropriately reflecting the gestures proposed by the rite. The various moments in the Liturgy require a musical expression of their own. From time to time this must fittingly bring out the nature proper to a specific rite, now proclaiming God’s marvels, now expressing praise, supplication or even sorrow for the experience of human suffering which, however, faith opens to the prospect of Christian hope.” Chirograph on centenary of Pius X Motu
"The Christian community must make an examination of conscience so that the beauty of music and song will return increasingly to the liturgy." 2003.
Pope Paul VI
Down the centuries, Gregorian chant has accompanied liturgical celebrations in the Roman rite, has nourished men's faith and has fostered their piety, while in the process achieving an artistic perfection which the Church rightly considers a patrimony of inestimable value and which the Council recognized as "the chant especially suited to the Roman liturgy."
Venerable Pope Pius XII
"Thus, at the instance and under the sponsorship of the Church, sacred music, through the course of centuries, has traversed a long road by which, though sometimes slowly and laboriously, it has finally reached the heights: from the simple and natural Gregorian modes, which are, moreover, quite perfect in their kind, to great and even magnificent works of art which not only human voices, but also the organ and other musical instruments embellish, adorn and amplify almost endlessly. Just as this progress in the art of music shows clearly how dear to the heart of the Church it was to make divine worship more resplendent and appealing to Christian peoples, so too it made clear why the Church also must, from time to time, impose a check lest its proper purposes be exceeded and lest, along with the true progress, an element profane and alien to divine worship creep into sacred music and corrupt it."
Pope St. Pius X
“Sacred music, being a complementary part of the solemn liturgy, participates in the general scope of the liturgy, which is the glory of God and the sanctification and edification of the faithful. It contributes to the decorum and the splendor of the ecclesiastical ceremonies, and since its principal office is to clothe with suitable melody the liturgical text proposed for the understanding of the faithful, its proper aim is to add greater efficacy to the text, in order that through it the faithful may be the more easily moved to devotion and better disposed for the reception of the fruits of grace belonging to the celebration of the most holy mysteries.”