But why had science lost its way in the first place? What appeal could these teachings of Pythagoras and Plato have had for their contemporaries? They provided, I believe, an intellectually respectable justification for a corrupt social order. The mercantile tradition that had led to Ionian science also led to a slave economy. You could get richer if you owned a lot of slaves. Athens in the time of Plato and Aristotle had a vast slave population. All that brave Athenian talk about democracy applied only to a privileged few.

40 min 35 sec - Cosmos: A Personal Voyage (1990 Update) - The Backbone of Night