Back in the Sixties, in his West End play The Bed-sitting Room, Spike Milligan liked to capitalize, in a different way each night, on his audience’s obligation to stand for the national anthem. So, for one performance, he came on in a diving suit, opened his helmet, put in a comb and tissue paper, closed his helmet and, from inside, played “God Save The Queen.” When everyone was on his feet, he popped open his helmet and said, “If you’ll stand for that, you’ll stand for anything.”

No audience, no joke. We’re part of the show; we always are—or we should be. At the more ambitious, non-Milligan end of the scale is a moment from Hal Prince’s stage production of Cabaretthat I cited in these pages a few years ago. Joel Grey, as the Kit Kat Klub’s emcee, is singing “If You Could See Her Through My Eyes” to a gorilla in a tutu. It’s a funny novelty number, and, on the last line, he turns to the audience and gleefully hisses, “If you could see her through my eyes … she wouldn’t look Jewish at all.” We laugh before we realize what we’re laughing at—and then we catch our reflections in the slanted mirror above the stage, and the laugh dies in a shaming silence. By conscripting the audience, Prince makes the moment more vivid than it could be in a novel or a film. Perhaps, if you played it to an audience of metaphor-attentive