“I’ll help you,” she said, “and we won’t need to go anywhere. Poirot says all you need to solve a mystery is ‘the little gray cells.’ ”

“Poirot?” I said. “Who’s Poirot? The curate?”

“No,” she said.“Hercule Poirot. Agatha Christie. He says—”

“Agatha Christie?” I said, completely lost.

“The mystery writer. Twentieth Century. My assignment before Lady Schrapnell took over Oxford and my life, was the 1930s, and it’s an absolutely grim time: the rise of Hitler, worldwide depression, no vids, no virtuals, no money to go to the cinema. Nothing at all to do except read mystery novels. Dorothy Sayers, E.C. Benson, Agatha Christie. And crossword puzzles,” she said, as if that explained everything.

“Crossword puzzles?” I said.

“Are not particularly useful to our present situation. But mystery novels are. Of course they’re usually about murder, not robbery, but they always take place in a country house like this, and the butler did it, at least for the first hundred mystery novels or so. Everyone’s a suspect, and it’s always the least likely person, and after the first hundred or so, the butler wasn’t anymore—the least likely person, I mean—so they had to switch to unlikely criminals. You know, the harmless old lady or the vicar’s devoted wife, that sort of thing, but it didn’t take the reader long to catch on to that, and they had to resort to having the detective be the murderer, and the narrator, even though that had already been done inThe Moonstone. The hero did it, only he didn’t know it. He was sleepwalking, in his nightshirt, which was rather racy stuff for Victorian times, and the crime was always unbelievably complicated. In mystery novels. I mean, nobody ever just grabs the vase and runs, or shoots somebody in a fit of temper, and at the very end, when you think you’ve got it all figured out, there’s one last plot twist, and the crime’s always very carefully thought out, with disguises and alibis and railway timetables and they have to include a diagram of the house in the frontispiece, showing everyone’s bedroom and the library, which is where the body always is, and all the connecting doors, and even then you don’t have a prayer of figuring it out, which is why they have to bring in a world-famous detective—”

“Who solves it with little gray cells?” I said.

“Yes. Hercule Poirot, that’s Agatha Christie’s detective, and he says it isn’t at all necessary to go running about measuring footprints and picking up cigarette ends to solve mysteries like Sherlock Holmes. That’s Arthur Conan Doyle’s detective—”

 — Chapter Twelve, To Say Nothing of the Dog by Connie Willis

     Inspired by reading Magpie Murders (watching the television adaptation both written by Anthony Horowitz) and re-reading Death on the Nile after watching a recent cinematic adaptation, I recall to mind the movie “Murder by Death” which parodied many of the well-known detectives of literature but excluded the most prominent one. I knew there was something . . ., for the want of a better word, special about Sherlock Holmes compared to the others like Miss Marple. Now I am able to pinpoint the difference between Holmes vs., say, Miss Marple and Hercule Poirot. Each represent two major epistemological schools of thought.

     Doyle’s Holmes mysteries are a proto-police procedural akin to current day “NCIS” where the murder mystery is solved through gathering physical evidence and deducing who the suspect is. Compared to the more Marple or Poirot approach, clues are sprinkled throughout the mystery novel leaving the reader to discern for themselves what clues matter and how only to be corrected by the detective using “the little gray cells” linking selected clues that point to the guilty party. Poirot’s approach is the Rationalists school e.g. Descartes, Spinoza. Whereas Holmes, evidence collecting before naming the likely suspect represents the Empiricist tradition e.g. Bacon, Hume.