The Cambridge History of English and American Literature in 18 Volumes (1907–21). VOLUME XVII. Later National Literature, Part II. VIII. Mark Twain. § 22. Naturalistic Pessimism; What is Man? The Mysterious Stranger. Mark Twain counts as an influence because he is an innovator. The great notes of his innovation from Innocents Abroad to A Connecticut Yankee are; first, the disillusioned treatment of history; second, the fearless exploitation of “the natural man,” or, the next thing to it, “the free-born American”; and, lastly, a certain strain of naturalistic pessimism. In the first class go the foreign-travel books. The Prince and the Pauper, and A Connecticut Yankee; and the impulse properly proceeding from them is imaginative satire. In the second class go Roughing It, Tom Sawyer, Life on the Mississippi, Huckleberry Finn, Adam’s Diary, and Eve’s Diary; and from such work has proceeded an observable impulse to the cultivation of the indigenous, the elemental, the primitive, and, perhaps, the brutal and the sensual. For the third class one can glean representative paragraphs only here and there among the writings published in Mark Twain’s lifetime; but the posthumously published philosophical dialogue What is Man? (1905) and The Mysterious Stranger (1916), a romance, and some of the letters are steeped in a naturalistic melancholy and tinged with a philosophical bitterness of which American literature before Mark Twain showed hardly a trace. That strain seems likely to be influential too, and, unfortunately, not always in connection with the fine bravado of his American faith, which occasionally required an antidote to its natural insolence.   31