There was probably a time in the life of Plato when the ethical teaching of Socrates came into conflict with the metaphysical theories of the earlier philosophers, and he sought to supplement the one by the other. The older philosophers were great and awful; and they had the charm of antiquity. Something which found a response in his own mind seemed to have been lost as well as gained in the Socratic dialectic. He felt no incongruity in the veteran Parmenides correcting the youthful Socrates. Two points in his criticism are especially deserving of notice. First of all, Parmenides tries him by the test of consistency. Socrates is willing to assume ideas or principles of the just, the beautiful, the good, and to extend them to man (compare Phaedo); but he is reluctant to admit that there are general ideas of hair, mud, filth, etc. There is an ethical universal or idea, but is there also a universal of physics?--of the meanest things in the world as well as of the greatest? Parmenides rebukes this want of consistency in Socrates, which he attributes to his youth. As he grows older, philosophy will take a firmer hold of him, and then he will despise neither great things nor small, and he will think less of the opinions of mankind (compare Soph.). Here is lightly touched one of the most familiar principles of modern philosophy, that in the meanest operations of nature, as well as in the noblest, in mud and filth, as well as in the sun and stars, great truths are contained. At the same time, we may note also the transition in the mind of Plato, to which Aristotle alludes (Met.), when, as he says, he transferred the Socratic universal of ethics to the whole of nature.