25 Art certainly must be listed among the noblest manifestations of human genius. Its purpose is to express in human works the infinite divine beauty of which it is, as it were, the reflection. Hence that outworn dictum "art for art's sake" entirely neglects the end for which every creature is made. Some people wrongly assert that art should be exempted entirely from every rule which does not spring from art itself. Thus this dictum either has no worth at all or is gravely offensive to God Himself, the Creator and Ultimate End.
Source: Musicae Sacrae (Vatican.va)