How did power emerge? Why has the art of war always been an organ propelling human evolution? Kant wrote that conflict and war are part of our natural condition, that there will forever be an Us against a You. Will we have to smooth over cultural differences in order to live together in peace? Will we have to have a sole world law, creed and currency? Or, as Jacques Attali writes, will we end up in a world war, all against all? During the Cold War in 1985, Reagan and Gorbachev agreed about one thing: that they would become allies if aliens invaded the earth. Us against Them.