This completes the exposition of the positive teaching of Socrates. It only remains for us to consider what position Socrates holds in the history of thought. There are two sides of the Socratic teaching. In the first {150} place, there is the doctrine of knowledge, that all knowledge is through concepts. This is the scientific side of the philosophy of Socrates. Secondly, there is his ethical teaching. Now the essential and important side of Socrates is undoubtedly the scientific theory of concepts. It is this which gives him his position in the history of philosophy. His ethical ideas, suggestive as they were, were yet all tainted with the fallacy that men are governed only by reason. Hence they have exercised no great influence on the history of thought. But the theory of concepts worked a revolution in philosophy. Upon a development of it is founded the whole of Plato's philosophy, and, through Plato, the philosophy of Aristotle, and, indeed, all subsequent idealism. The immediate effect of this theory, however, was the destruction of the teaching of the Sophists. The Sophists taught the doctrine that truth is sense-perception, and as the perceptions of different individuals differ in regard to the same object, it followed that truth became a matter of taste with the individual. This undermined all belief in truth as an objective reality, and, by similar reasoning, faith in the objectivity of the moral law was also destroyed. The essential position of Socrates is that of a restorer of faith. His greatness lay in the fact that he saw that the only way to combat the disastrous results of the Sophistic teaching was to refute the fundamental assumption from which all that teaching flowed, the assumption, namely, that knowledge is perception. Against this, therefore, Socrates opposed the doctrine that knowledge is through concepts. To base knowledge upon concepts is to base it upon the universality of reason, and therefore to restore it from the {151} position of a subjective seeming to that of an objective reality.