In 1903, in the town of Great Wyrley, England, 27-year-old George Edalji was charged with severe animal mutilation. Up until then, Edalji was an upstanding citizen — the son of a vicar and a successful solicitor in his own right. But Edalji’s family had long faced discrimination for their Parsee—or Persian—heritage. The police received anonymous letters accusing George of the crimes. When a pony was found with its stomach slit open, they went in for the arrest. Officers found George’s clothing covered with mud, blood, and horse hair. The year was 1903, and that was evidence enough for the law. It was not enough for George. So he sent a letter to his favorite mystery author asking for help—and incredibly, Sir Arthur Conan Doyle took the case.

Rarely has a character revolutionized a genre the way Sherlock Holmes did the mystery. Of course George Edalji wrote to Conan Doyle; who else knew how to catch a bank robber by the dirt on his pants, or a gem thief by his goose-selling habits? October 2017 marks the 125th anniversary of the first Holmes novel, “A Study in Scarlet”—and since then, the word “mystery” has invariably evoked Sherlock Holmes. But Edalji was onto something when he enlisted Conan Doyle in his real-life crime case. Sherlock Holmes crossed the border between real life and fiction with a persuasiveness that changed the relationship between author and audience. “A Study in Scarlet” was something new for the world of mysteries—but it was also something new for the world in general.

For his part, Conan Doyle never planned for his stories to explode as they did. The author was a serious man — Sherlock Holmes was child’s play. But for Conan Doyle’s audiences, Holmes was a character they could claim for themselves. “A Study in Scarlet” was first published in “Beeton’s Christmas Annual,” an English magazine, in 1887. By 1893, when Conan Doyle pushed Holmes off a cliff, the mysteries’ influence was great enough that 20,000 Strand magazine subscribers cancelled their subscriptions. Today, such fervor is normalized: Being a “fan” is an identity, and liking something often has elements of culture and community. But when Sherlock Holmes was new, such passion was almost unheard of. Fans protested in the streets and wrote their own endings. Even J.M. Barrie—the author of “Peter Pan” and a personal friend of Conan Doyle—wrote a Sherlock Holmes piece of his own. An especially dramatic subset of Sherlock adherents claimed that Conan Doyle was just the literary agent for the “real” Holmes and Watson.

By having such little regard for his own characters, Conan Doyle inadvertently shifted the dynamic between author, audience, and artwork. His audiences felt so strong an affinity for his stories that the author’s own intentions ceased to matter. This wasn’t about Conan Doyle, the person. This was about Sherlock Holmes. The character was so ubiquitous that he became the standard to which all subsequent mysteries were compared. Holmes and Watson are the original clinical-genius-with-friendly-sidekick pair. The archetype is so powerful that it is hard to know when an adaptation is an allusion to Conan Doyle, and when it is just something created post-Holmes. The BBC show “Sherlock” is an explicit riff on the original stories, for example, but what about the medical drama “House” (with remarkably similar characters), or the mystery-comedy “Psych” (with a remarkably similar conceit)? The prototype is Conan Doyle’s. Everything that comes later has Holmes to thank.

Conan Doyle might be gratified to know that his work had such influence within his genre. But as a trained doctor, he might be even happier to hear about the real science that his writing influenced. Conan Doyle brought science to mystery writing—and the result was both captivating for audiences and inspirational for real-life detectives. Sherlock Holmes was the first to use ballistics, including bullet trajectory, as evidence in a criminal case. He used scientific methods to analyze blood spatters and deduce poisonings. The first real forensics lab was built in 1910, 23 years after Conan Doyle built the first fictional one. If Conan Doyle had an astounding influence on the mystery genre and the concept of a “fan,” he had almost as much on real detectives. He became a powerful figure in criminal justice—making him an obvious person to turn to if, say, you were accused of animal mutilation in a small English village.

George Edalji didn’t kill all those animals in Great Wyrley. Conan Doyle proved it: There was no blood on Edalji’s property, the soil was from the wrong place, and the police wrapped a piece of horsehide in Edalji’s clothing. The real perpetrator was a local butcher with violent tendencies. Conan Doyle shouted the news of his solved mystery; he wrote lengthy articles for the “Telegraph,” with a request that they go uncopyrighted. The police, however, remained unconvinced. The butcher was not charged. Conan Doyle ran into the same Lestrade-esque police force that he created for Holmes: Life imitated art with cruel accuracy. What Conan Doyle brought to the world—detective work based on empirical science—was something the world wasn’t quite prepared for. Holmes’ standards of scientific evidence would take decades to permeate the justice system. One could argue that they still haven’t. The new concept of “audience” advanced by Sherlock fans would be readily embraced—but Conan Doyle’s ideas about justice have proven much more difficult to realize.So happy birthday, Sherlock Holmes. You can’t fall off your cliff for good quite yet. A lot has changed in 125 years, but we still need the detective work you represent. We still need the enthusiasm for rigorous, factual evidence that you incited. The year is 2017—and we still need you.