Journalist Peter Warne (Clark Gable, barely visible at right) and runaway heiress Ellie Andrews (Claudette Colbert, not visible here) watch fellow bus passengers dance awkwardly to “The Daring Young Man on the Flying Trapeze,” in my favorite moment from Frank Capra’s It Happened One Night.

Though the heart-string tugging of both this scenario and the below-decks feiseanna from Titanic  — another movie about a wealthy young woman sneaking away, perhaps only temporarily, from her gilded cage — are manipulative, it’s important to distinguish between the polished middlebrow sentimentality of James Cameron’s spectacle and Capra’s mushy emotional idealism. (Ellie to Peter, in their previous scene: “Awww, I like mushy stuff!”)

Barbara Ehrenreich’s Dancing in the Streets: A History of Collective Joy is an excellent book — but Capra’s off-kilter blocking here reveals everything you’ll ever need to know about what Ehrenreich calls the value of spontaneous, ecstatic group celebration.