This book stands against the current of judgments long settled in the schools of law in regard to classic cases such as Lochner v. New York, Near v. Minnesota, the Pentagon Papers case, and Bob Jones University v. United States. Professor Hadley Arkes takes as his subject concepts long regarded as familiar, settled principles in our law - "prior restraints," ex post facto laws - and he shows that there is actually a mystery about them, that their meaning is not as settled or clear as we have long supposed. Those mysteries have often given rise to illusions or at least a series of puzzles in our law. They have at times acted as a lens through which we view the landscape of the law. We often see what the lens has made us used to seeing, instead of seeing what is actually there. Arkes tries to show, in this text, that the logic of the natural law provides the key to this chain of puzzles.