Political Philosophy or the philosophical theory of the State has closer relations with history than any other branch of philosophical inquiry. It is indeed distinguished from history in that it can disregard the success or failure, the historical development of this or that state. For it is concerned not with historical happenings but with ideals, not with the varying extent to which different states have approximated or fallen short of their purpose, but with that purpose itself, not, in short, with states but with _the_ State. Yet this need not involve that the ideal, _the_ State, is always and everywhere the same. Ideals are born of historical circumstances and fashioned to meet historical problems, and the would-be timeless ideals which political philosophers have put before us have always borne clear marks of the country and time of their origin. The ideal which men have set themselves in political organization has varied from time to time. That such variation is inevitable will be clear if we ask ourselves what we can possibly mean by an ideal state. That states fall short of their ideal because of the imperfections of their citizens is clear enough. All political life demands a certain standard of moral behaviour, of capacity to work for a common good, and an understanding of the results of our own and other people's actions. Were human selfishness completely overcome, the state would still be necessary to correct individual shortsightedness. The policeman, exempt from the cares of apprehending criminals, would still be needed to control traffic. But imagine, not that all citizens attained a certain standard of moral and intellectual behaviour, as the ideal demands, but that they were all perfectly good and perfectly wise, should we need any kind of government at all? Is not the supposition of perfection so far removed from any state of affairs we can really think of or plan for, that it cannot enter into our reckoning, ideal or practical? Every ideal takes certain facts of human life for granted whilst it tries to improve others. All ideal states, Plato's as well as others, assume certain facts about human nature and human society. These facts may and do vary. The Greek city state assumed that a state must be small, if it was to have the intensive life they demanded. The Roman Empire was a denial of the anarchy to which the Greek ideal had led, but it lost in intensity what it gained in extent. All political ideals assume a certain sociological background on which the state is based and from which spring the problems which the state is intended to solve. As this sociological background varies from time to time, _the_ State, the purpose which men set before themselves in political organization, will vary also. The Greek city state and the mediaeval state were not different approximations to the same ideal. They were the expressions of different ideals. They rested on different assumptions, e.g. as to the place of authority in society.