Energy is the basis of modern civilization; it dominates the headlines, makes and breaks the economy of nations, determines their foreign policy. Yet it is relatively a newcomer to history. It began to occupy men's minds only during the Middle Ages, not before. Egypt, Assyria, Persia, all fashioned their empires without it, Greece achieved her glory and Rome her splendor without it. Very possibly the glory and the splendor would have been still greater, had Greeks and Romans turned their attention to utilizing sources of power other than the muscles of man or beast. For some reason they did not.