The history of Western thought is often presented as a smooth progression from ancient philosophy through the Enlightenment to modern science and democracy. The reality was far bloodier. Nearly every major advance in how human beings understand themselves, their governments, and the natural world was achieved through violent conflict, persecution, and the destruction of older ways of thinking. The evolution of modern thought was not a gentle awakening but a series of brutal collisions between incompatible worldviews. The ancient Greek philosophers who laid the foundations of Western rational inquiry were themselves operating in societies built on slavery and conquest. Socrates was executed by democratic Athens for the crime of asking uncomfortable questions. The philosophical schools that survived him did so by carefully navigating political power  ...