4. Today the world is entering a new era of revolution. The fourth wave of fresh, turbulent dynamics to confront America since Jefferson gamely predicted those centuries of virtuous prosperity back in that 1787 letter to Madison. Driven by incredible technological shifts and their economic, military and social implications, new forces are beginning to tear into the established global order. Among the most fundamental puzzles now is the problem of an American national mission. What does America seek to achieve in the world? And how? On what basis will the United States secure the chance to continue “peaceably”, as Jefferson would have it? Because the country plays such a central role, these questions’ answers will affect the calculations of every nation, of every new force yearning for influence. They represent the crucial background against which we will all live, build businesses, travel and learn. You might feel, sitting in Silicon Valley or Iowa, that such shifts don’t matter to you now, but the cold truth is that the international system is unlikely to be arranged, in two or three decades’ time, along the lines that bind it now. Too many violent forces are at work. But must this be a disaster? The technological demands of our age are forcing a new sensibility everywhere. Research labs, medicine, science, finance and the arts are all hunting now for anew outlook. The need for a fresh perspective is also reflected in the biggest of all historical questions, the one that will decide if we live in an era of peace or one of fear, uncertainty and tragedy: How is the international system to be ordered? The idea that the stability of the world system might honestly be at stake right now feels incredible to the generations of Americans born after World War II. A struggle for global order? Real, sharp, bloody nation-imperiling violence? Though we know such traps are a recurring feature of human history, we have been mostly numbed and reassured by the passing of optimisti