Mark Twain has been called the American Cervantes, our Homer, our Tolstoy, our Shakespeare. Ernest Hemingway maintained that "all modern American literature comes from one book by Mark Twain called Huckleberry Finn." President Franklin Delano Roosevelt took the phrase "New Deal" from A Connecticut Yankee in King Arthur's Court. Twain's Gilded Age gave an entire era its name. Twain is everywhere--in ads for Bass Ale, in episodes of "Star Trek," as...