Sir Arthur Conan Doyle (1859-1930), best known as the author of Sherlock Holmes stories but also a devout spiritualist, was entirely convinced by a set of photographs apparently showing two young girls from Cottingley in Yorkshire playing with a group of tiny, translucent fairies. To demonstrate his unshakeable belief in the spirit world, he published The Coming of the Fairies in 1922. Doyle's book lays out the story of the photographs, their...