Man is the measure of all things," said the early Greek philosopher, Protagoras of Abdera. It was in this spirit of humanistic self-confidence that in the first half of the sixth-century B.C., Greek-speaking thinkers inaugurated the western philosophical tradition. In the Greek colonies of western Asia Minor, Thales, Anaximander, and Anaximenes postulated a physical universe based on natural laws. Then in Croton in southern Italy, Pythagoras, enraptured by geometry and music, formulated th...