There may or may not be an epidemic of autism, but the idea of 'autism' has been remarkably catching. Once understood as a vanishingly rare condition, identified only in 1943, decades after Sigmund Freud and his followers first explored the psychopathology of childhood, autism has become commonplace. Popular culture celebrates it as an amusing quirk, often embodied in the figure of the boy genius, and some people attribute everyday failures of empathy, tact, or etiquette to their perpetrators being 'on the spectrum'. How did we get to this point?