"Hauntings are memes, especially pernicious thought contagions, social contagions that need no viral or bacterial host and are transmitted in a thousand different ways. A book, a poem, a song, a bedtime story, a grandmother's suicide, the choreography of a dance, a few frames of film, a diagnosis of schizophrenia, a deadly tumble from a horse, a faded photograph, or a story you tell your daughter."