If you believe what he said on 60 Minutes not long ago, even Bob Dylan is in awe of the staggering leaps he took when he made a mountain of art from the molehill folk scene he transcended in the early '60s. This change wasn't a simple organic process of redefinition or refinement, or some kind of amalgam of influences emerging during a hi-Zeitgeist era, but like the Mad Hatter he sometimes emulated back then, Dylan had stepped through a Looking Glass into another dimension altogether. It seems clear, in retrospect, that he evidently felt it necessary to pull himself free after Blonde on Blonde and, for better or worse, he never quite made it back. This two-CD set, which accompanies Martin Scorsese's bio-documentary that runs on PBS on September 26 and 27, is an illustration of his half-decade of glory. There are his earliest homemade tapes, the Guthrie-channeled early songs, and a variety of outtakes and live moments running through 1966, showing a once-in-a-lifetime visionary at work during his peak -- and it's unlikely we'll ever see anything like it again.