Christopher describes photographs taken in 1917 that appear to show live fairies. The incident was called “The Case of the Cottingley Fairies,” and Sir Arthur Conan Doyle, author of the Sherlock Holmes stories, uses the photographs as proof of the existence of fairies. In actuality, the fairies shown were just cut outs, which the photographers admitted in 1981. Christopher explains Occam’s razor, a law that says “no more things should be presumed to exist than are absolutely necessary.” To Christopher, this means that murderers tend to know their victims, fairies don’t exist, and you can’t talk to the dead.