The problem of knowing : Pope Leo the Great and Attila the Hun -- The illusion of power : Henry VIII and Francis I -- The inevitability of surprise : Cortés and Moctezuma -- The principle of contingency : Metternich, Castlereagh, Talleyrand and others -- The false lessons of history : Wilson, Clemenceau, and Lloyd George -- The rule of unintended consequences : Roosevelt, Churchill, and Stalin -- The fantasy of realism : Bush, Kohl, Mitterand and others.