17. Influence of Socrates. -- Socrates made a very profound and lasting impression on philosophic thought. As the first fruit of his teaching, there arose a number of lesser Socratic Schools, which kept only part of his moral legacy, and even continued to draw from the Sophists whom their master had consistently opposed. The Schools of Megara and Elis (fourth and third centuries) formulated an abstract and Eleatic doctrine on the Good; the Cynic school sought the realization of practical virtue; the Cyrenaic school returned to the sensualist ethics of Protagoras. Socrates' greatest influence was felt elsewhere. It came from his dialectic of definition and from his original conception of science. From this conception Plato and Aristotle were destined to elaborate a complete philosophical synthesis.