At the end of the fifth book Plato introduces the figment of contingent matter, which has exercised so great an influence both on the Ethics and Theology of the modern world, and which occurs here for the first time in the history of philosophy. He did not remark that the degrees of knowledge in the subject have nothing corresponding to them in the object. With him a word must answer to an idea; and he could not conceive of an opinion which was an opinion about nothing. The influence of analogy led him to invent ‘parallels and conjugates’ and to overlook facts. To us some of his difficulties are puzzling only from their simplicity: we do not perceive that the answer to them ‘is tumbling out at our feet.’ To the mind of early thinkers, the conception of not-being was dark and mysterious; they did not see that this terrible apparition which threatened destruction to all knowledge was only a logical determination. The common term under which, through the accidental use of language, two entirely different ideas were included was another source of confusion. Thus through the ambiguity of (Greek) Plato, attempting to introduce order into the first chaos of human thought, seems to have confused perception and opinion, and to have failed to distinguish the contingent from the relative. In the Theaetetus the first of these difficulties begins to clear up; in the Sophist the second; and for this, as well as for other reasons, both these dialogues are probably to be regarded as later than the Republic. BOOK VI. Having determined that the many have no knowledge of true being, and have no clear patterns in their minds of justice, beauty, truth, and that philosophers have such patterns, we have now to ask whether they or the many shall be rulers in our State. But who can doubt that philosophers should be chosen, if they have the other qualities which are required in a ruler? For they are lovers of the knowledge of the eternal and of all truth; they are haters of falsehood; their meaner desires are absorbed in the interests of knowledge; they are spectators of all time and all existence; and in the magnificence of their contemplation the life of man is as nothing to them, nor is death fearful. Also they are of a social, gracious disposition, equally free from cowardice and arrogance. They learn and remember easily; they have harmonious, well-regulated minds; truth flows to them sweetly by nature. Can the god of Jealousy himself find any fault with such an assemblage of good qualities?