The great political thinkers of the world have always been clear in their own minds as to the ultimate goal of their own particular study. Political thought may be said to have originated with the Jewish prophets, who were the first to rebuke kings to their faces and to set forth the spiritual aims of politics--to preach Righteousness and Mercy as against Power and Ambition and Self-interest. Their soaring imagination, less systematic than the Greek intellect, was wider in its sweep and more farseeing in its predictions. 'As the earth bringeth forth her bud and as the garden causeth the things sown in it to spring forth', says Isaiah, in magnificent anticipation of the doctrine of Natural Law, 'so the Lord God will cause righteousness and praise to spring forth before all the nations.' 'Peace, peace, to him that is far off, and to him that is near, saith the Lord, and I will heal him: but the wicked are like the troubled sea when it cannot rest, whose waters cast up mire and dirt. There is no peace, saith my God, for the wicked.' 'Out of Zion shall go forth the Law and the word of the Lord from Jerusalem. And he shall judge between the nations and shall reprove many peoples; and they shall beat their swords into plowshares and their spears into pruning hooks: nation shall not lift up sword against nation, neither shall they learn war any more.'[61] It was, however, Plato and Aristotle who first made politics a branch of separate study: and, unlike many of their modern successors, they pursued it throughout in close connexion with the kindred studies of ethics and psychology. Their scope was, of course, confined to the field of their own experience, the small self-contained City-States of Greece, and it did not fall within their province to foreshadow, like the Jewish Prophets, the end of warfare, or to speculate on the ultimate unity of mankind. Their task was to interpret the work of their own fellow-countrymen on the narrow stage of Greek life. Their lasting achievement is to have laid down for mankind what a State is, as compared with other forms of human association, and to have proclaimed, once and for all, in set terms, that its object is to promote the 'good life' of its members. 'Every State', says Aristotle in the opening words of his _Politics_, 'is a community of some kind.' That is to say, States belong to the same _genus_, as it were, as political parties, trade unions, cricket clubs, business houses, or such gatherings as ours. What, then, is the difference between a State and a political party? 'If all communities', he goes on, 'aim at some good, the State or political community, which is the highest of all and which embraces all the rest, aims, and in a greater degree than any other, at the highest good.'