This lecture was given as the Alec Roche Lecture 2006 at New College, Oxford, under the title 'The Idea of International Society'. Professor Allott re-recorded the lecture on 8 July 2014 at the Faculty of Law, University of Cambridge. If the intergovernmental world of diplomacy and war and international politics is re-classified under the category of 'madness', that might help us to understand better the scale of the challenge that we face in trying to re-make that world in the light of the age-old idea of the natural social unity of all-humanity. This entry provides an audio source for iTunes U.