One of the most impressive elements of a Phish concert, aside from the crackerjack light show, is the degree to which fans personally invest themselves in the music. When a song is performed sloppily or a solo doesn’t last as long as it could have, there is an odd sort of familial disappointment, like a son’s embarrassment at his father’s shortcomings. But when the music is strong, it’s like a feedback loop that drives the band higher and higher. You can see it on stage and you can see it in the crowd.