Disagreements and debates are common among Grateful Dead fans but there is a surprising consensus that the show the group gave at Barton Hall at Cornell University on May 8, 1977 is one of the band's greatest. It, like so many Dead shows, first gained its reputation through tape trading, but its legend soon eclipsed Deadhead circles, culminating in its induction into the Library of Congress's National Recording Registry in 2012. Rhino/Grateful Dead Records' official release followed in May 2017 -- just in time for the concert's 40th anniversary; it was also bundled as part of a big box called Get Shown the Light, which contains all the shows the Dead did in May 1977 -- and it's worth the wait. Sourced from the original soundboard recordings by Betty Cantor-Jackson, the sound is colorful and vivid, an excellent complement to a prime Dead performance. What makes this such an exceptional performance isn't that it's the Grateful Dead at their most experimental -- not only is there no "Dark Star," there is no "Drums>Space" spotlight -- but at their warmest. From the moment the band launches into "New Minglewood Blues," it's evident they're in a good mood, and they run through a set that draws heavily on party songs and cowboy tunes while finding space for delicate moments, such as a lovely "Morning Dew." If this isn't the best Grateful Dead show ever -- a hard thing to quantify -- it's nevertheless at the sweet spot of providing hardcore Deadheads with plenty to savor while offering a good introduction for neophytes, which is more than enough to make it essential.