During the axial period of classical Greek philosophy (roughly 500-200 B.C.E.), philosophers posed virtually every question that it is possible to ask concerning the world, humanity, God, and the meaning of life. Different schools of philosophy gave different answers to these questions. Some of these answers have proved wrong (e.g., Aristotle's contention that rest is the natural state of motion of a physical body), some have proved true (e.g., Archimedes'...