In Paleolithic times, the T-shirt was a humble tool, worn beneath a shirt, to absorb perspiration. But ever since James Dean started wearing one without anything on top, it morphed into a form of personal advertising, a movable billboard. Even Dean’s plain white shirt conveyed a powerful message, which was, You can’t tell me who to be, a declaration that has never gone out of style. From the hippies in their tie-dyes to the disaffected metal kid I just saw in Washington Square Park wearing a gothic-stenciled Goatwhore T-shirt, the primary social function of a T-shirt has stayed the same.