``Another scintillating collection of brilliant problems and paradoxes by the most entertaining logician and set theorist who ever lived.`` -- Martin Gardner ``Smullyan is not your run-of-the-mill puzzlemeister; he polishes up old chestnuts, spins variations on a theme, and peoples his logical world with a delightful cast of characters.`` -- Science 82 ``I believe Ray Smullyan to be the Lewis Carroll of our times. His little books of logic puzzles will be remembered long after most of us are forgotten.`` -- Peter Denning, Chairman of the Computer Science Department, Naval Postgraduate School ``You may experience small frissons of delight as you follow Smullyan into the dizzying heights of Godel's proof and the very nature of proof, truth, and logic in mathematics.`` -- Kirkus Reviews Discover scintillating new perspectives on the principles of mathematical logic with this puzzle treasury. Inspired by the classic tale of a prisoner's choice between two doors, these whimsically themed challenges allow readers to base their decisions on logic rather than luck. Nineteen chapters advance from relatively simple puzzles and meta-puzzles to highly complex paradoxes involving probability, time, and change. The author, a well-known philosopher and magician as well as a celebrated mathematician and logician, was acclaimed by The New York Times as ``a master at translating difficult ideas into stories and puzzles that require no formal background, only patience and a passion to learn.