Nor is the _Republic_ an instance of Utopian theorising. It is a criticism of contemporary Greek civilisation, intended to remove the greatest practical difficulty in life. Man has tried all kinds of governments and found none satisfactory. All have proved selfish and faithless, governing for their own interests only. Kings, oligarchs, democrats and mob-leaders have without exception regarded power as the object to be attained because of the spoils of office. Political leadership is thus a direct means of self-advancement, a temptation too strong for weak human nature. As a well-known Labour leader hinted, five thousand a year does not often come in men's way. There is only one way of securing honest government and that is Plato's. A definite class must be created who will exercise political power only, economic inclinations of any sort disqualifying any of its members from taking office. The ruling class should rule only, the money-making class make money only. In this way no single section will tax the rest to fill its own pockets. The one requisite is that these Guardians should be recognised as the fittest to rule and receive the willing obedience of the rest. If any other sane plan is available for preserving the governed from the incessant and rapacious demands of tax-collectors, no record of it exists in literature. Practical statesmanship of a high and original order is manifest in the _Republic_; in England, where the official qualifications for governing are believed to be equally existent in everybody whether trained or untrained in the art of ruling, the _Republic_, if read at all, may be admired but is sure to be misunderstood. It seems that Plato's teaching at the Academy raised formidable criticism. The next group of dialogues is marked by metaphysical teaching. The _Parmenides_ is a searching examination of the Ideas. If these are in a world apart, they cannot easily be brought into connection with our world; a big thing on earth and the Idea of Big will need another Idea to comprehend both. Besides, Ideas in an independent existence will be beyond our ken and their study will be impossible. Socrates' system betrays lack of metaphysical practice; at most the Ideas should have been regarded as part of a theory whose value should have been tested by results. This process is exemplified by a discussion of the fundamental opposition between the One and the infinite Many which are instances of it. This criticism shows the advantage Plato enjoyed in making Socrates the mouthpiece of his own speculations; he could criticise himself as it were from without. He has put his finger on his own weak spot, the question whether the Ideas are immanent or transcendent. The results of this examination were adopted by the Aristotelian school, who suggested another theory of Knowledge.