I was among those who felt some affection for the Grateful Dead’s 1967 debut album, but perhaps that’s because I hadn’t seen them live by the time of its release. Most people who had—including the group themselves—said that the record paled in comparison. It barely made a dent in the charts and garnered weak reviews.

The gap between the Dead’s live shows and their studio work bothered the band, but the lack of commercial success apparently didn’t. Instead of looking for a hit in the wake of their disappointing debut, they focused on capturing the improvisational nature of their concerts and on innovating. They spent so long on these pursuits—half a year—that Joe Smith, the Warner Bros. A&R man who’d signed the band, wrote to them to insist that they promptly wrap up and send over the masters. The Dead responded by underlining the passages they most disliked in…