The procedure adopted by Plato is curiously opposed to that which might seem natural to a modern thinker on politics. The scepticism which was to be met, having sprung from the extremity of class-antagonism, it might be supposed that the cure would be sought in some sort of system of equality. Plato's idea is precisely the contrary. The distinction between classes he exaggerates to its highest point; only he would have it depend on degrees, not of wealth, but of excellence. In the ideal republic which he constructs as a type of a state where justice should really rule, he sets an impassable gulf between the governing class and the governed; each is specially trained and specially bred for its appropriate function; and the harmony between them is ensured by the recognition, on either part, that each is in occupation of the place for which it is naturally fitted in that whole to which both alike are subordinate. Such a state, no doubt, if ever it had been realised in practice, would have been a complete reply to the sceptical argument; for it would have established a "justice" which was the expression not of the caprice of the governing class, but of the objective will of the whole community. But in practice such a state was not realised in Greece; and the experience of the Greek world does not lead us to suppose that it was capable of realisation. The system of stereotyping classes--in a word, of caste--which has played so great a part in the history of the world, does no doubt embody a great truth, that of natural inequality; and this truth, as we saw, was at the bottom of that Greek conception of the state, of which the "Republic" of Plato is an idealising caricature. But the problem is to make the inequality of nature really correspond to the inequality imposed by institutions. This problem Plato hoped to solve by a strict public control of the marriage relation, so that none should be born into any class who were not naturally fitted to be members of it; but as a matter of fact the difficulty has never been met; and the system of caste remains open to the reproach that its "justice" is conventional and arbitrary, not the expression of the objective nature and will of all classes and members of the community.