It was performance art with an extremely cool audience (and an extremely cool performance group): “At times, the event took on a mystical cast, Ms. Knowles and her troupe extending their arms toward the crowd in a kind of benediction. The effect was moving, the show itself museum-worthy. As Nat Trotman, the Guggenheim curator of performance and media, noted, it was part of a tradition that dates from the late 1960s, when Meredith Monk first performed in the rotunda.”