In most of Mark Twain's major novels, mistaken identity is the central plot device and satiric device. The main variation is the romantic convention of the disguised aristocrat who undertakes an incognito journey, which appears in The Prince and the Pauper. A Connecticut Yankee. The American Claimant, Huckleberry Finn, and The Mysterious Stranger. It is the structural principle of plot organization in The Prince and the Pauper and The American Claimant, and one major episode in A Connecticut Yankee is based on the romantic convention. In all three novels it is adapted as a satiric vehicle and a3 an example of Twain's theories of determining training and environment. The initial device of switched identities—the change of clothes between commoner and aristocrat—forces the aristocrat into an incognito journey, which becomes a moral pilgrimage as his ingrained ideas give way to the new environmental forces that are brought to bear on him. The journey motif offers the satirist a wide scope to display the crimes of a hereditary aristocracy in The Prince and the Pauper and A Connecticut Yankee and the inequalities of American democracy in The American Claimant. The simple formula of the educational journey initiated by the device of switched identities appears also in Twain's masterpiece, Huckleberry Finn. In the characters of the King and the Duke, Twain treats on a burlesque level the romantic convention of the aristocrat in disguise, for the purpose of uniting his satiric themes of the moral depravity of a slave-holding aristocracy and the detrimental effects of romantic literature. He uses the romantic conventions again in the controversial conclusion to draw his incipient tragedy back into the realm of comedy and farce. In The Mysterious Stranger, mistaken identity is used on both the allegorical and psychological-philosophical levels of the narrative action as the organizing structural principle and as a vehicle for Twain's theories of determinism and for his condemnation of the damned human race." In the allegory, Satan-Philip Traum is the celestial aristocrat in disguise who journeys to the earth to observe the peculiarities of the human species. He is both satiric observer and Theodor Fischer's mentor in disillusionment as he takes him on supernatural journeys around the earth and instructs him about the Moral Sense and Twain’s theories of determinism. On the psychological-philosophical level of the action, Satan is Theodor's reason arriving at progressive realizations of the absurdity of the human predicament. The Mysterious Stranger is thus related to Twain’s comic fantasy, "The Facts Concerning the Recent Carnival of Crime in Connecticut," in which he presents the dual personality of man and conscience. In Pudd'nhead Wilson. Twain uses the convention of changelings in the cradle as his central plot device. The switch of identities between master and slave is used to satirize slavery and to illustrate the effects of environment and training on behavior. In one of its aspects, Pudd'nhead Wilson is the detective thriller, and the mistaken identity plot, with its inherent confusion of appearance and reality and the possibilities that it offers for dramatic unraveling, furnishes the necessary suspense.