Of all the musical developments of rock in the 1960s, one in particular fundamentally changed the music’s structure and listening experience: the incorporation of extended improvisation into live performances. While many bands—including Cream, Pink Floyd, and the Velvet Underground—stretched out their songs with improvisations, no band was more identified with the practice than the Grateful Dead. In Get Shown the Light Michael Kaler examines how the Dead’s dedication to improvisation stemmed from their belief that playing in this manner enabled them to touch upon transcendence....