The beginning of western philosophy........

     In 490-470 B.C. Sparta and Athens, forgetting their jealousies and joining forces, fought off the effort of the Persians under Darius and Xerxes to turn Greece into a colony of an Asiatic empire.  In this struggle of youthful Europe against the senile East, Sparta provided the army and Athens the navy.  The war over, Sparta demobilized her troops, and suffered the economic disturbances natural to that process, while Athens turned her navy into a merchant fleet, and became one of the greatest trading cities of the ancient world.  Sparta relapsed into agricultural seclusion and stagnation, while Athens became a busy mart and port, the meeting place of many races of men and of diverse cults and customs, whose contact and rivalry begot comparison, analysis and thought.
      Traditions and dogmas rub one another down to a minimum in such centers of varied intercourse; where there are a thousand faiths we are apt to become sceptical of them all.  Probably the traders were the first sceptics; they has seen too much to believe too much;  and the general disposition of merchants to classify all men as either fools or knaves inclined them to question every creed.  Gradually, too, they were developing science; mathematics grew with the increasing complexity of exchange, astronomy with the increasing audacity of navigation.  The growth of wealth brought the leisure and security which are 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, "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.

-Will Durant,  The Story of Philosophy