Many factors went into that most transportive of phenomena: a great Dead show. But the most essential one was Jerry Garcia's musical temperature on a given night. There are no worries on that front here; from his lyrical lines on a nearly 20-minute "Sugaree" (sounding at times like the cooing of birds) to his angular, electronically processed explorations on a similarly expansive "Not Fade Away," the guitarist is firing on all pistons. So are his bandmates, likely excited to have an album's worth of great new material (Terrapin Station) to play. Terrapin would be released two months later, and the band had already spent much of the year playing the songs live. From the cubist reggae of "Estimated Prophet" to the complex, art-rock song suite that gave the album its name, the Dead lit the tunes ablaze on that spring evening in Hartford.