See also THIS.
Extract (pp. 2-3):
The central principle of American political belief is that the government derives legitimacy from the consent of the governed. This is a subversive and divisive idea, an invitation to revolution, incompatible, one might suppose, with successful government of a vast and diverse state. But it has been sufficiently achieved in the Constitution and practice of the United States to have become on the whole a source of strength. It can dissolve empires, but it can also be a potent, attractive and adhesive force for the nation that can exemplify it.