, wrote John Locke, 'must be our best judge and guide in every thing.' In so speaking, Locke epitomised a bright confidence in reason, widespread, which was born of the Enlightenment. More recently, however, such confidence has been lost as reason has revealed its own limits, one by one – not merely practical, but theoretical – limits which frequently would seem impassable. These are the limits which Noson Yanofsky addresses. The survey is expansive, and adept.