The years 800-200 BCE comprise one of the most creative and influential eras in world history. Karl Jaspers termed this epoch "the Axial Age," to indicate its pivotal importance in the evolution of human thought. The ferment of religious and philosophical activity centered in four distinct regions of civilization: East Asia, South Asia, West Asia, and the Northeastern Mediterranean. Each of these areas witnessed the emergence of several imaginative individuals whose exemplary lives and teachings prompted their followers to create the traditions that led to the birth of the world religions. Zoroaster, Jeremiah, Isaiah, Gautama Buddha, Confucius, Pythagoras, Socrates, Plato, and Aristotle side by side, we are able to see more clearly the questions with which they struggled, their similarities and differences, and how their ideas have influenced religious thought down to our day.