Stylistically, [the music of Led Zeppelin] is a tour de force, borrowing from Bo Diddley, the Stones, Cream, and Burt Bacharach, fusing jazz, rock, blues, flamenco. It is persuasive and snarling, whether acoustic or electric. It is deceptively facile, yet almost never overblown. It relies heavily on the blues for its emotional strength, yet has expanded the vocabulary of that ill-used idiom while remaining firmly locked within it. Some maintain that, like the best or the worst of rock, Page and his troupe have been schooled in the art of excess. They play too loud and too long. Yet the musical evidence dumbfounds such a view. A song like "Stairway to Heaven" is characteristic; it begins quietly with acoustic guitar playing an aching quasi-blues melody. The singer stutters out the simplest of themes. Gradually, but inevitably, the sound develops over ten minutes into a massive climax, the bass...