How Watson Learnt the Trick is a Sherlock Holmes parody written by Arthur Conan Doyle in 1924. It concerns Doctor Watson attempting to demonstrate to Holmes how he has learned the latter's "superficial trick" of logical deduction by giving a summary of Holmes' current state of mind and plans for the day ahead, only for Holmes to then reveal that every single one of Watson's deductions is incorrect.Conan Doyle was one of several authors commissioned to provide books for the library of Queen Mary's Dolls' House; others included J. M. Barrie, Thomas Hardy, Rudyard Kipling and W. Somerset Maugham. Conan Doyle was provided with a book approximately 1.5" x 1.25" (3.75 cm x 3.15 cm) into which he wrote the 503-word story of How Watson Learned the Trick by hand, taking up 34 pages. The original manuscript is still part of the Dolls' House library.