On the Decay of the Art of Lying is a short essay written by Mark Twain in 1885 for a meeting of the Historical and Antiquarian Club of Hartford, Connecticut. In the essay, Twain laments the dour ways in which men of America's Gilded Age employ man's "most faithfull friend." He concludes by insisting that: "the wise thing is for us diligently to train ourselves to lie thoughtfully, judiciously; to lie with a good object, and not an evil one; to lie for others' advantage, and not our own; to lie healingly, charitably, humanely, not cruelly, hurtfully, maliciously; to lie gracefully and graciously, not awkwardly and clumsily; to lie firmly, frankly, squarely, with head erect, not haltingly, tortuously, with pusillanimous mien, as being ashamed of our high calling."

Among the most significant works Mark Twain: The Gilded Age: A Tale of Today, The Prince and the Pauper, A Connecticut Yankee in King Arthur's Court, The American Claimant, Pudd'nhead Wilson, Personal Recollections of Joan of Arc, A Horse's Tale, The Mysterious Stranger, The Adventures of Tom Sawyer, Adventures of Huckleberry Finn, Tom Sawyer Abroad, Tom Sawyer, Detective, "Schoolhouse Hill", The Mysterious Stranger, "Huck Finn and Tom Sawyer among the Indians", "Huck Finn", "Tom Sawyer’s Conspiracy", "Tom Sawyer’s Gang Plans a Naval Battle".