From page 547-8 The Life of Mark Twain - The Middle Years 1871-1891:

Sam resumed work on A Connecticut Yankee as soon as he arrived in Elmira with his family on June 23, 1888. Much as he had composed most of the latter half of Huck Finn at Quarry Farm during the summer of 1883, he wrote chapters 21-36 of his new novel that summer. In his octagonal study overlooking the city, he assayed a number of social theories in the crucible of his imagination. He perused yet again Carlyle’s History of the French Revolution that summer and glossed on the flyleaf of his copy: “The Revolution had a result—a superb, a stupendous, a most noble & sublime result—to wit, French Liberty, & in a degree, Human Liberty—& was worth a million times what it cost, of blood, & terror, & various suffering, & titanic labor.” In a preface to the novel drafted that summer, he suggested that “human liberty—for white people—may fairly be said to be one hundred years old this year,” the centenary of the French Revolution. Under the influence of Carlyle’s and William E. H. Lecky’s histories, Sam wrote and interpolated chapter 10, “Beginnings of Civilization,” into the narrative to forestall the criticism that he had not adequately described the advances the Yankee had introduced to sixth-century Camelot. Eventually named Hank Morgan (after the German adverb morgen, meaning “tomorrow”), the man from the future with historical hindsight “started a teacher-factory and a lot of Sunday-schools the first thing” to educate the people. He nationalized the mines, a pipe dream in Orion Clemens's Nevada. He founded “man-factories” modeled on the U.S. Military Academy at West Point to train experts and technicians, though he kept them out of sight lest they attract the attention of vassals and varmints.  In brief, Morgan hails the imminent inauguration of the millennium in a paragraph studded with metaphors of violence and assault better suited to apocalypse:

My works showed what a despot could do with the resources of a kingdom at his command. Unsuspected by this dark land, I had the civilization of the nineteenth century booming under its very nose! It was fenced away from the public view, but there it was, a gigantic and unassailable fact—and to be heard from, yet, if I lived and had luck. There it was, as sure a fact and as substantial a fact as any serene volcano, standing innocent with its smokeless summit in the blue sky and giving no sign of the rising hell in its bowels... I stood with my hand on the cock, so to speak, ready to turn it on and flood the midnight world with light at any moment.

Henry Nash Smith and others have argued, partly on the basis of this paragraph, that Sam was an agnostic about the inevitability of progress. As Everett Carter puts it, this passage in particular betrays Sam’s fear that human evolution “through technology is the wrong course for humanity. Comparing technology to a hell the metaphor seems on the face of it to be loaded with negative feelings about the beneficence of applied science.” Rather than contributing to the material comfort of the nation, technology is almost without exception deployed in the novel as an instrument of murder and mayhem: the destruction of Merlin’s tower, the assassination of knights with hand grenades and guns, the electrocution of knights during the holocaust of the Sand Belt, and so forth. Or as Smith explains, Sam “had planned a moral fable illustrating how the advance of technology fosters the moral improvement of humanity. But when he puts his belief to the test by attempting to realize it in fiction” he discovered “that his belief in progress and human perfectibility was groundless.” Neither a dystopian romance set in the future like George Orwell’s 1984 (1949) nor a utopian romance set in the future like Edward Bellamy’s Looking Backward (1888), A Connecticut Yankee is best described, in the words of James M. Cox, as an “inverted utopian fantasy’ set in the past. Whereas Bellamy affirmed the perfectibility of human nature and the inevitability of progress, Sam fundamentally questioned “the beneficient effect of industrialism” and insinuated that nineteenth-century civilization had “threatened rather than fulfilled human happiness.”