Here are a few highlights from Feast of Faith (I'll leave the other book for a separate post as this is already getting rather long):
It is astonishing to find that in the German edition of the documents of Vatican II, edited by Karl Rahner and Herbert Vorgrimler, the brief commentary which introduces the chapter on Sacred Music in the Constitution on the Liturgy begins with the observation that genuine art, as found in church music, is "of its very nature - which is esoteric in the best sense - hardly to be reconciled with the nature of the liturgy and the basic principle of liturgical reform". It is astonishing because the Constitution on the Liturgy, on which it is supposed to be commenting, does not see music as "merely an addition and ornamentation of the liturgy" but as itself liturgy, an integrating part of the complete liturgical action. (pg. 97)
Comparing the Council document itself with the commentary by Rahner and Vorgrimler, we find a contrast which is characteristic of the difference, in general, between what the Council said and how it has been taken up by the postconciliar Church. (pg. 99)
The years which followed witnessed the increasingly grim impoverishment which follows when beauty for its own sake is banished from the Church and all is subordinated to the principle of "utility". (pg. 100)
As opposed to a narrow, rationalistic theory of proclamation, we would need to point to that cosmic proclamation which finds expression in Psalm 19: the heavens are telling the glory of God. The Creator's glory cannot be manifested in word only: it needs to be expressed in the music of creation, too, and in its creative transformation by the mind of the believing and beholding man. At the same time we would need to remind ourselves that the psalms are also the prayers of the poor, the prayer of the crucified Righteous One, and as such they are to a large extent laments; but here too they are to be seen as the lament of the whole creation, which goes beyond words, transforming them into a music in which the lament becomes both a beseeching of God and a sign of hope: glory, too, but in the mode of suffering.
"Glorification" is the central reason why Christian liturgy must be cosmic liturgy, why it must as it were orchestrate the mystery of Christ with all the voices of creation. (pg. 115)
Thomas says that through the praise of God man ascends to God. Praise itself is a movement, a path; it is more than understanding, knowing and doing - it is an "ascent", a way of reaching him who dwells amid the praises of the angels. Thomas mentioned another factor: this ascent draws man away from what is opposed to God. Anyone who has ever experienced the transforming power of great liturgy, great, art, great music, will know this. Thomas adds that the sound of musical praise leads us and others to a sense of reverence. It awakens the inner man...
Vatican II was well advised, therefore, only to indicate very general standards: music must "accord with the spirit of the liturgical action"; it must be "suitable, or be capable of being "made suitable, for sacred use"; it must "accord with the dignity of the temple" and "truly contribute to the edification of the faithful".