WE ARE living in what is, by all odds, the most tumultuous type of historical epoch. Ever since the invention of the city some six or seven thousand years ago and the quick advance of urban societies into the habit of empire building, the periods of collapse between imperial systems have been, without exception, the times of greatest violence, uncertainty, and confusion-and yet of potential creativeness. At the apex of society, citizens have waited, with apprehension or ambition, to discern the next center of power-after Sumer and Akkad, Nineveh, after Nineveh, Babylon, after Babylon, Thebes, after Thebes, Alexandrian Greece, after Greece, Rome. A similar sequence of competing rising and collapsing imperialisms can be discerned in every continent. Even the Chinese endured half a millennium of “civil” war before the Chin dynasty re-established unified government, and then Mongol conquerors and Manchu dynasts were still to follow. It may be that the Buddha’s concept of life as a “melancholy wheel” has its basis not so much in the revolving constellations and returning harvests as in the deadly repetition of imperial rise, conquest, decline, and fall.