In A Study in Scarlet, Sherlock Holmes’s best quip wasn’t “the game’s afoot!” but instead, something a little more intelligent. “What you do in this world is a matter of no consequence,” Holmes tells Watson. “The question is what can you make people believe you have done.” Playing the game of perception versus truth is probably just as essential to the canon Sir Arthur Conan Doyle’s Sherlock Holmes as the search for obscure clues. But, how did a fictional character convince us he has a real birthday, and why are we still (sometimes) confused about his age?

On Saturday, Sherlock Holmes fans — sometimes called Sherlockians, sometimes Holmsesians, sometimes Baker Street Babes —celebrated the “real” birthday of the greatest detective in history. On January 6, in either 1853 or 1854, William Sherlock Scott Holmes, son of Siger and Violet Holmes, youngest brother of Mycroft and Sherrinford Holmes, was born. Most fans will tell you it’s certainly 1854 (not 1853) and the most revered Holmes scholar of them all, Leslie Klinger, settles on 1854, too. Writing in 2005’s The New Annotated Sherlock Holmes, Klinger says that the timeline of the life of Holmes consists of a “…consensus of the major chronologists.” What this means, is that Klinger is like all fans who have played “the game,” the original fan theory community in which readers pretend Sherlock was a real person, albeit one with biographical source material limited to 56 short stories and four novels. As Ian McQueen elucidates in his 1974 book Sherlock Holmes Detected, “The only direct reference to [Sherlock’s] age comes from the very last adventure of all, “His Last Bow,” when Holmes, alias the Irish-American Altamont, is described as ‘a tall, gaunt man of sixty.’ The age sixty may not have been precise, but is suggestive of Holmes having been born about 1853 or 1854.”

LEFT: Vintage cover for 'His Last Bow,' the collection which contains the story of the same name. RIGHT: Benedict Cumberbatch as Sherlock Holmes in the 2013 'Sherlock' episode "His Last Vow."

That’s right. The only direct reference in the canon to Sherlock’s age comes from a story in which he’s straight-up not really supposed to be himself. While there are many things just as on-brand for Sherlock Holmes, few correlate as perfectly with the awesome Study in Scarlet quote about making people believe things about yourself that may not correspond with reality. In the story “The Empty House,” we find out Holmes faked his death but did he also fake his own life? It’s a weird question to ask of a fictional character, but because so many scholars (read: super fans) still act as though he lived, the impossible, becomes merely, the improbable. Or, to put it another way, just because someone is made-up, doesn’t mean they can’t have a “real” birthday.

So, sure, “His Last Bow,” says Holmes was about 60 in 1914, so his birthday is therefore in 1854. That’s fine. But why January 6? Where on Baker Street did that come from? Bizarrely, the concept comes from Christopher Morely. He’s the guy who helped establish the first biggest Holmes fan organization, The Baker Street Irregulars. In one of the early fan meetings, Morely simply decided Holmes was born on the 12th day of Christmas (January 6) because Sherlock Holmes references the Shakespeare play Twelfth Night twice in the canon.

Christopher Morley, one of the founders of the Baker Street Irregulars.

That’s it. A really influential fan decided that Holmes was obsessed with Twelfth Night because it reminded him of his own birthday. Analogously, this makes about as much sense as everyone’s theories about Supreme Leader Snoke’s backstory in Star Wars: The Last Jedi.

But, unlike something like Star Wars, the keepers of true Sherlock Holmes canon have been, for over a hundred years, the fans. So, happy 164th birthday Mr. Holmes. From your biggest fans to you. And then let’s have one more toast for us again.