In 1917, two young cousins claimed they played with fairies by a stream. They took photos of themselves with the fairies, and many people (including Sir Arthur Conan Doyle, who penned the Sherlock Holmes tales) believed they were real.
But, in the end, they were – alas! – revealed to be a hoax.
Christopher concludes that "Occam's razor," - a theory that says the simplest explanation is the right one – must be correct.