Three or four years ago, rock reviewing was less problematic than it is today. For one thing, you knew what to write about. The Byrds, the Animals, the Dead, the Airplane, and the Beach Boys were fit subjects for comment; Gerry and the Pacemakers, Dave Clark and Freddie and the Dreamers were not. The Beatles, the Stones, and Dylan were the first inductees to rock's (as opposed to rock and roll's) pantheon; after that, everyone bowed in the direction of San Francisco and underground British groups until the appearance of Led Zeppelin.

Zeppelin forced a revival of the distinction between popularity and quality. As long as the bands most admired aesthetically were also the bands most successful commercially (Cream, for instance) the distinction was irrelevant. But Zeppelin's enormous commercial success, in spite of critical opposition, revealed the deep division in what was once thought to be a homogeneous...