..the avant-garde aesthetic is a simple one. but the severe risk run by those who subcribe to it is twofold; partly that means may be mistaken for ends - the striking of a fresh posture, the adoption of an untried process, may be mistaken in itself for an art-work, which it is not; and partly that, by thus shifting the scale of values, the concept of permanent validity in the finished work becomes relative. your novelty the next, if you have no other yardstick by which to measure it than the fact of its progressiveness"


give two muscal "styles" from the twenieth century that, in your opinion, have not gone beyond just being novel. contrast them with two other styles from the twentieth century that you think have proven to have more than just "ephemeral validity" support you answers by dicussing specific musical examples, at least one per style..