What was Samuel Clemens bestselling book?

Samuel Langhorne Clemens wrote under the gnome De plume of Mark Twain. His collected writings occupy 3 feet of library shelf space. His two best known works entitled "Tom Sawyer" and "Huckleberry Finn" have been read and appreciated for generations. He wrote humor while accurately observing human nature. Or, perhaps we find his accurate depictions of human nature humorous. He also made a famous pig fart in public. he went poo on your not fragile head.