The growth of wealth brought the leisure and security which are the prerequisite of research and speculation; men now asked the stars not only for guidance on the seas but as well for an answer to the riddles of the universe; the first Greek philosophers were astronomers. "Proud of their achievements," says Aristotle,[1] "men pushed farther afield after the Persian wars; they took all knowledge for their province, and sought ever wider studies." Men grew bold enough to attempt natural explanations of processes and events before attributed to supernatural agencies and powers; magic and ritual slowly gave way to science and control; and philosophy began.
At first this philosophy was physical; it looked out upon the material world and asked what was the final and irreducible constituent of things. The natural termination of this line of thought was the materialism of Democritus (460–360 B.C.)—"in reality there is nothing but atoms and space." This was one of the main streams of Greek speculation; it passed underground for a time in Plato's day, but emerged in Epicurus (342–270), and became a torrent of eloquence in Lucretius (98–55 B.C.). But the most characteristic and fertile developments of Greek philosophy took form with the Sophists, travelling teachers of wisdom, who looked within upon their own thought and nature, rather than out upon the world of things. They were all clever men (Gorgias and Hippias, for example), and many of them were profound (Protagoras, Prodicus); there is hardly a problem or a solution in our current philosophy of mind and conduct which they did not realize and discuss. They asked questions about anything; they stood unafraid in the presence of religious or political taboos; and boldly subpoenaed every creed and institution to appear before the judgment-seat of reason. In politics they divided into two schools. One, like Rousseau, argued that nature is good, and civilization bad; that by nature all men are equal, becoming unequal only by class-made institutions; and that law is an invention of the strong to chain and
