Mark Twain claimed he could read human character as well as he could read the Mississippi River. Now one of America s preeminent Twain scholars has interwoven the author s inner life with his writings to produce a meditation on how Twain s understanding of human nature evolved and deepened. Quirk charts the ways in which this humorist and occasional philosopher contemplated human nature, revealing how his outlook changed over the years. His travels, his readings in history and science, his political and social commitments, and his own pragmatic testing of human nature in his writing contributed to Twain s mature view of his kind. Quirk establishes the social and scientific contexts that clarify Twain s thinking, and he considers not only Twain s stated intentions about his purposes in his published works but also his ad hoc remarks about the human condition.