In the early seventies, King Crimson, Yes, Jethro Tull, Emerson, Lake and Palmer, and many others brought forth a series of adventurous and visionary works, often of epic length. Responding both to the new possibilities in rock music opened up by Sergeant Pepper's Lonely Hearts Club Band, as well as to the countercultural politics and aesthetics of the late sixties, these musicians applied consummate instrumental and compositional skill to transgressing...