The Greek doctrine that the essence of the state consists in community of purpose is the counterpart of the notion often held in modern times that the essence of the state is force. The existence of force is for Plato and Aristotle a sign not of the state but of the state's failure. It comes from the struggle between conflicting misconceptions of the good. In so far as men conceive the good rightly they are united. The state represents their common agreement, force their failure to make that agreement complete. The cure, therefore, of political ills is knowledge of the good life, and the statesman is he who has such knowledge, for that alone can give men what they are always seeking. If the state is the organisation of men seeking a common good, power and political position must be given to those who can forward this end. This is the principle expressed in Aristotle's account of political justice, the principle of "tools to those who can use them." As the aim of the state is differently conceived, the qualifications for government will vary. In the ideal state power will be given to the man with most knowledge of the good; in other states to the men who are most truly capable of achieving that end which the citizens have set themselves to pursue. The justest distribution of political power is that in which there is least waste of political ability. Further, the belief that the constitution of a state is only the outward expression of the common aspirations and beliefs of its members, explains the paramount political importance which Aristotle assigns to education. It is the great instrument by which the legislator can ensure that the future citizens of his state will share those common beliefs which make the state possible. The Greeks with their small states had a far clearer apprehension than we can have of the dependence of a constitution upon the people who have to work it. Such is in brief the attitude in which Aristotle approaches political problems, but in working out its application to men and institutions as they are, Aristotle admits certain compromises which are not really consistent with it.