European statesmanship, as revealed in the Treaty of Versailles, and in the conduct of international affairs since the Armistice, has recognised neither the fact of interdependence-the need for the economic unity of Europe-nor the futility of attempted coercion. Certain political ideas and passions give us an unworkable Europe. What is their nature? How have they arisen? How can they be corrected? These questions are part of the problem of sustenance;...