In common usage, gesture names the emptiest of social forms. You reach to help someone, knowing already that they’ve got it. Somewhere between reflex and performance, a gesture signals good intentions without the burden of follow-through—we call this a “mere gesture.” At the same time, a gesture can be understood as the smallest, most basic unit of power as it gets made and remade through embodied social relations. A handshake in a back room is only the most obvious example. We raise our hand to speak, or we don’t. We reach out to some and not to others. We return somebody’s gaze, but only if the conditions are right. In its etymological sense, gesture (from the Latin gerere, to carry or conduct) signals a question of comportment, of how the body conducts itself (Noland and Ness 2008). Critical concern about what gesture conveys—about what kind of meaning it carries—dates back at least as far as the Protestant Reformation, when debates over the performance of sacrament sought to secure a distinction between true belief and the bodily image of devotion, or merely going through the motions. The Oxford English Dictionary notes this usage in The Book of Common Prayer (1549), where...