Azar Nafisi is an enthusiast. In the epilogue to her book, “The Republic of Imagination,” she states that she began her analysis (but, really, celebration) of American literature intending to write about 24 books. She ended up choosing three: “The Adventures of Huckleberry Finn,” “Babbitt” and “The Heart is a Lonely Hunter.” In these works by Mark Twain, Sinclair Lewis and Carson McCullers, she finds the essence of the American experience, filtered through narratives not about exceptionalism or fabulous success, but alienation, solitude and landscape.