Sherlock Holmes is the ultimate survivor. Multiple media keeps him alive long after his creator Sir Arthur Conan Doyle's death.

A pipe-smoking detective who sports a deerstalker and has few social graces sounds like an implausible icon of pop culture, let alone one that has survived since his first public appearance in 1887. I propose that the cleverest puzzle yet solved by Sherlock Holmes is the attainment of near-immortality. His creator Sir Arthur Conan Doyle was forced to resurrect him after bumping him off — and ironically, Holmes continues to thrive in multiple media even after Doyle's death.

Post-Doyle, any possible variant of the Holmes story that you can think of has been written: Holmes in his customary Victorian setting, solving fresh cases; Holmes in different time periods; Holmes battling mythical creatures ranging from zombies and vampires to Count Dracula and Dr. Jekyll. The Mandala of Sherlock Holmes: The Missing Years by Jamyang Norbu brings Holmes closer home, to India and Tibet, while Andrew Lane's Death Cloud published last year kicks off, Holmes adventures for the young-adult market. We've never let the detective with the steel-trap mind die.

The art of pastiche may be a selfless one, but it is a money-spinning form of altruism when it comes to Holmes. Currently we have two ongoing Holmes franchises that are very successful — with two very different actors playing Holmes to great effect, on TV by Benedict Cumberbatch and in films by Robert Downey Jr.

Downey, famous in his own right, grabbed our attention when he and director Guy Ritchie created a steampunk Sherlock (2009), who uses his fists as effectively as his razor sharp mind, the whole delivered with Downey's ironic charm offensive. While the sequel, “A Game of Shadows” does feel a bit “more of the same”, it is entertaining — and Downey is a Holmes that we like to watch.

Cumberbatch on the other hand — despite appearances in “Atonement and Tinker Tailor Soldier Spy” — was largely unknown when he appeared last summer in BBC's pilot episode of Sherlock in the 21st century, slyly titled “A Study in Pink”.

Clever writing

It was a pretty big task, to make the Victorian hero seem credible in contemporary times, where he deals with clues embedded in mobile phones and a blog-happy Watson. But thanks to some clever, clever writing by Steven Moffat and Mark Gatiss, and a bravura performance by Cumberbatch, it's some of the most addictive TV I've seen in a long time.

Cumberbatch's Holmes might be updated by replacing the pipe with nicotine patches, but he has nailed, totally, the essence of the original idiosyncratic genius. Even Steven Spielberg has been quoted as saying that Cumberbatch is “the best Sherlock Holmes on screen”.

The TV series also has the luxury of time — and the imagination — to sneak in details from the originals, such as folks from London's homeless underclass being in Holmes' payroll; as well as players such as Sherlock's brother Mycroft developed into a full-blown character.

But what, you may well ask, is the constant that runs through the perpetual reinventing and reimagining? What's the essential heart of the Holmesian narrative that needs to be preserved, which keeps us coming back for more? As Holmes himself would have explained: “When you have eliminated the impossible, whatever remains, however improbable, must be the truth".

In other words, the secret of his success is the fascination exerted by “Holmesian deduction”: The detective comes up with an explanation, seemingly pulled out of a hat that surprisingly turns out to be true. He then explains to us goggle-eyed mortals how it is done, through a process of careful observation, inductive study and drawing inferences about the best possible explanation. For example at the crime scene of a dead woman wearing pink (in the current TV series' episode A Study in Pink), he insists there must be a missing suitcase, which he proceeds to find; Holmes noticed a splash of mud on her leg that he deduces must have been thrown up by the wheel of a suitcase.

As Downey's Holmes says, his “curse” is that he sees quite literally “everything”.

The Canon of Sherlock Holmes — ie the stories written by Doyle himself — is surprisingly small, just 60 adventures comprising four novels and 56 short stories. It makes his far-reaching influence all the more remarkable.

Almost every gumshoe thereafter that I can think of, owes some sort of allegiance to 221B Baker Street's violin-playing hero, from Agatha Christie's Hercule Poirot to Hugh Laurie's Dr. Gregory House in the popular TV series “House”, to the forensics of CSI. Holmes, interestingly enough, is said to be based on a real man, Dr. Joseph Bell, a renowned forensic scientist at Edinburgh University.

Apart from the definitive detective archetype, Holmes and his friend/chronicler Dr. Watson also set the template for subsequent buddy tales and bromances about oddly matched or goodcop/badcop duos. Dr. Watson is the regular guy like you or me, who works as the prism through which we see the eccentricities of the hero's genius.

The prototypes continue in Professor Moriarty, Holmes' archenemy and one of the first examples of the super villain who is as brilliant as the hero, but having taken his intellect over to the dark side — sounds familiar? — is almost more powerful than the hero. Shadowy Moriarty is the precursor to Bloefeld, Lex Luthor, and all other superbaddies so necessary as counterpoint to every hero. It's not that Moriarty appears a great deal in the Holmes' canon, rather it's the suggestion of his presence; as Guy Ritchie has said, Moriarty “really has become the most famous villain in literature, for not doing a great deal, either, by the way.”

Not quite elementary, but there you have it: The explanation of the secret of the near-immortal detective. Case Closed. At least, for now.