I think that much of the illiberalism of Plato grows out of his theory of knowledge. To him as to Socrates, knowledge is of universals. Mere awareness of concrete objects we will agree is not knowledge. If we only knew unrelated things--just one thing and then another, as we have them in sense experience, we could have knowledge _of_ them but not _about_ them. It is the knowledge about things that gives the world its meanings. Much of the significance of things depends upon how we conceive their relations. Every concept is an abstraction; it signifies not some concrete fact, but a class or a common quality which inheres in a number of objects. So the Greeks sought to find concepts which would not be self-contradictory and would hold for all of the class to which they were applied, and for nothing else. The Greeks did not seek accurate information concerning facts. They believed they had exact knowledge when they had discovered just what they meant by any concept. They had almost no experimental science. They had begun to be deeply interested in the phenomena of nature but their interest was largely speculative as yet. If they had possessed the modern scientific laboratory their knowledge could still have been abstract but it would have remained knowledge about nature. Knowledge would have increased as men carefully observed objects, classified them, studied their relations and made note of the changes which take place under fixed conditions. By the method of forming hypotheses and then trying to verify them by fact, knowledge could have been at once both of the universal and of the concrete. It would have been recognized all along that universals are merely descriptive terms signifying common properties and that they do not stand for realities which are independent of or outside the several individual objects in which these properties are found. With Socrates, I believe, knowledge is about universals, but he is primarily concerned with attaining clear and workable abstractions, that is, he is interested chiefly in sharpening the _instruments_ of thinking.