As much as Christopher likes Sherlock Holmes, he doesn’t like Sir Arthur Conan Doyle, who wrote the stories. He believed in the supernatural, which Christopher finds ridiculous. Christopher describes the 1917 case of the Cottingley fairies, in which two girls supposedly captured photographs of fairies. It was later discovered that the fairies were actually pieces of paper that the girls had set up to fool everyone—and they succeeded. Sir Arthur Conan Doyle wrote an article saying he thought the fairies were real. Christopher thinks that the fact that the fairies in the photos look just like how fairies are described in old books proves they’re fake. Later, the girls admitted they had faked the photos.
Christopher’s dislike of the supernatural goes along with his dislike of imagining alternate realities. Essentially, he only likes provable truths. He doesn’t like speculating about what might exist—thus, he never speculates that his mother might be alive. In saying that the photographed fairies look too much like how fairies are supposed to look, Christopher echoes a similar assertion he made about alien spaceships. He thinks that even if such myths were true, humans couldn’t possibly have imagined them the way they actually exist.
Christopher thinks this story shows that sometimes people are willfully blind to the truth. Furthermore, it proves Occam’s razor, a law that claims that people shouldn’t assume that more things exist than are necessary. Essentially, everything usually has a simple, realistic explanation.
Again, Christopher’s view as an outsider gives him great perception about general human tendencies. Ironically, the story of his mother that he has yet to learn essentially breaks this law with the complexity that it adds to the mystery of Wellington’s death.