One hundred years ago, two girls went down to the stream at the bottom of a garden in Cottingley, England, and took some photographs of fairies. The fairies were paper cut-outs, which Elsie Wright, age 16, had copied from a children’s book. She and 10-year-old Frances Griffiths took turns posing with the sprites.

The girls developed the photographs in Elsie’s father’s darkroom, and presented them to their families as stunning evidence that fairies were real. Elsie’s father didn’t believe them—but her mother did. Two years later, she showed the photographs at a meeting of the Theosophical Society, a group dedicated to exploring unexplained phenomena and “forming the nucleus of a universal brotherhood of humanity.”

The story of the Cottingley fairies has always fascinated me—not because of the particulars of the case, but because of what it reveals about the life cycle of a lie. In contrast to other famous hoaxes, it doesn’t seem malicious, or even necessarily deliberate. Instead it seems to me to be a story about how a single, relatively small act of deception can lead a large group of people to lose control over the truth.

In the first photograph, Frances Griffiths stares somewhere to the right of the camera lens, pointedly not looking at the cardboard figures capering on the grass in front of her. In the second one, Elsie Wright leans forward to shake the hand of a toddler-sized boy fairy. Looking at them now, both photographs seem immediately identifiable as fakes. The figures are obviously propped-up and two dimensional. Everything, including the expressions on both girls’ faces, looks staged. It is hard to imagine the photos seeming convincing to anyone older than 12.

Yet the Theosophical Society saw things differently; the members immediately and ecstatically accepted the photographs as real. Edward Gardner, a writer and leading member of the Society, took them as proof that the “next cycle of evolution was underway” and mounted a campaign to convince the public of their authenticity. He gave lectures on the photographs, made copies of them, and passed them reverently around at meetings.

Initial press coverage was skeptical; one editorial noted that the photographs could be explained not by “a knowledge of occult phenomena but a knowledge of children.” But during and after World War I, spiritualism and mysticism gained increased influence over a grieving British public. The fairy photographs seemed to resonate with many people who were eager to believe in the existence of a better world, and in the possibility that we might be able to communicate with it.

Willingness to believe in the fairies was not a matter of intelligence or education. None other than Sir Arthur Conan Doyle, a trained physician and the creator of Sherlock Holmes, was dead-set on the whole notion. Doyle, a noted spiritualist, saw the photographs as evidence that communication could exists between material and spiritual worlds.

Doyle published an article about the photographs in The Strand magazine, and sent Gardner to visit the girls. Imagine being either Frances or Elsie at that moment. You have told a lie—a tale that started out as a joke, maybe, or a daydream. Now things are taking on a momentum that you cannot quite control. A stranger comes to your house with two cameras and says, No pressure, kids, but we would all just be thrilled to death if you could get us a few more shots of those fairies. Do you confess and make a fool out of everyone—or do you do what everyone clearly wants you to do, which is traipse off down to the stream and produce some more photographs?

The girls came back with three more pictures: Frances and the Leaping Fairy, Fairy Offering Posy of Harebells to Elsie, and Fairies and their Sun-Bath. These, too, look absurdly fake to modern eyes. But Gardner and Doyle fell for it again. Gardner then brought in a psychic, who claimed that the whole place was just crawling with fairies.

To me, the strangest part of this story is not that two girls pretended they knew some fairies, but rather that adults so badly wanted their encounters to be true. Not just Gardner and Doyle, whose reputations, by that point, were at least partially at stake. Lots of people were ready to believe. They twisted and massaged the narrative to add credibility. The social reformer Margaret Macmillan, for instance, emphasized that the photographers were children, and thus without motive or guile: “How wonderful that to these dear children such a wonderful gift has been vouchsafed.”

The novelist Henry de Vere Stacpool, meanwhile, insisted that the photographs were real because they just seemed truth-y: “Look at [Frances’] face. Look at [Elsie’s] face. There is an extraordinary thing called Truth which has 10 million faces and forms—it is God’s currency and the cleverest coiner or forger can’t imitate it.” The girls were telling the truth because they looked like they were telling the truth, and that was proof enough.

Eventually, people stopped caring about the fairies. Interest in the supernatural was on the wane, and Doyle was looking increasingly unhinged. The girls produced no more photographs, and the public moved on.

Every once in a while, though, someone would track down one of the girls and press them for more details, or try to get them to admit that they had been making it up. In 1983, they finally admitted that the photographs were faked, but maintained that they really had seen fairies. Elsie said that they were all faked, but Frances said that the last one was real. Frances’s daughter later insisted that fairies were real, and that her mother would never lie. You will still find corners of the internet today where people will say the same thing. Despite the girls mostly owning up to the lie, people still want to believe it, and so they will say that it is true.

The problem with telling a lie is that you often have to tell another one after that, to keep up appearances. And then it’s too late to admit what you made up, and so you just keep on lying. The issue becomes not the initial act of deception, but the fact that you’ve lied for so long—years and years and years. You may even start to believe the lie yourself. I have been thinking about it a lot lately, watching the news. Watching people on my TV lie; wondering if they even know that they are lying, as the stakes keep getting higher and higher.