The barbarians are always at the gate. Conflict is a natural consequence of the human condition. When these simple facts are ignored and the absence of conflict becomes a principle policy objective, a dangerous stage is set: the barbarians will recognize that you are willing to sacrifice fundamental principles in order to avoid conflict, and they will exploit that timidity. It is in vogue to argue that the lesson for America to draw from Edward Gibbon’s The History of the Decline and Fall of the Roman Empire is to avoid imperial overstretch and thus avoid the barbarians; 9/11 exposed the fallacy of that theory in today’s globalized world.