Reading Greil Marcus at his best — on Bob Dylan, Van Morrison, Sly Stone, the Band, Sleater-Kinney, Dock Boggs or Randy Newman, to name just a few of his obsessions over the years — is like watching a surfer glide shakily down the wall of an 80-foot wave, disappear under a curl for a deathly eternity, then soar out the other end. You practically feel like applauding. He makes you run to your iPod with an ungodly itch in your cranium. You want to hear what he hears. It’s as if he were daring you to get as much out of the music as he does.