The "age of the gods" in rock actually ended in about 1977, by which time the "canon" was all but fixed. Up to that point, it was a very open-ended art form, fueled by influences from all kinds of different genres of music and by the exuberant energies of a novel "youth culture" that, for the first time in world history, defiantly rejected the tastes and values of society's teachers and parents. The Beatles and the Who, Hendrix and the Doors, the Dead and the Airplane, the Zeps and the Sabs, ELP and Genesis, and all the rest had no "rock" predecessors to copy. In an era of heady experimentation, they fashioned new and hitherto unimagined musics from all manner of sources--Blues and R&B, folk, skiffle, jazz, and classical. And to a point, some more progressive elements in the record industry of the time encouraged them to do this. But after about 1977, there is a perceptible shift. The established acts either chose or were forced to pursue less ground-breaking, safer, more commercial sounds. The new acts were now schooled in the "canon" of rock and less likely to be fertilized by the sensibility-broadening influences from other forms, the inevitable results being, with a few notable exceptions, pretty "derivative." And since then, as whatizitman points out, even the canon itself has been relentlessly commodified, its once revolutionary sounds now endlessly pumped out of the ceilings of supermarkets.