Mark Twain's skeptical assessment of free will, and determinism, religious belief, and the nature of humanity. He put off publishing it for 25 years, and then released it anonymously in a limited edition of 250 copies. The book takes the form of a Socratic dialogue between a romantic young idealist and an elderly cynic, who debate such issues as whether personal merit is meaningless given how our environment shapes who we are, and whether man has any impulse other than pursuing pleasure and avoiding pain.