• "A scintillating collection of problems and paradoxes of logic from the most entertaining expert in mathematical logic and set theory who has ever lived. As in all his similar books, Professor Smullyan guides us through the Godelian tunnels underneath mathematical puzzles, which lead to beautiful theorems about truth and provability." —Martin Gardner

• "The meta-puzzle 'Who is the spy?' represents the most brilliant logic puzzle ever formulated..." —George Boolos

• "Smullyan is a gifted teacher. No matter from which angle we observe him, he always manages to confuse us. He is the perfect logician. The lightning quick reversals or unexpected endings of his stories convince us that he is a magician of mathematical logic." — The New York Times Book Review