Edgar Allan Poe . C. Auguste Dupin Arthur Conan Doyle . Sherlock Holmes Agatha Christie . Hercule Poirot . Miss Marple When I was in school learning and writing about Edgar Allan Poe — and invariably nodding off partway through "The Fall of the House of Usher" — I was introduced to C. Auguste Dupin, Poe's creation and invention, the ratiocinating detective. I … [Read more...] about Ratiocinate. A Very Good Word