"Hence, my four little tales are of no genuine ghosts in the scientific sense; they tell of no hauntings such as could be contributed by the Society for Psychical Research, of no specters that can be caught in definite places and made to dictate judicial evidence. My ghosts are what you call spurious ghosts (according to me the only genuine ones), of whom I can affirm only one thing, that they haunted certain brains, and have haunted, among others, my own and my friends'—yours, dear Arthur...