I have just finished reading Laurence Bergreen's Over the Edge of the World, an account of Magellan's circumnavigation of the globe. It is a ripping yarn, full of heroism and derring-do, horrifying privation and unexpected success (alas, not to be enjoyed by Magellan himself). It also depicts a time when life was cheap, torture and brutality were commonplace, kings and tribal chieftains had absolute power over their subjects, religious and racial intolerance were rife, ancient superstitions went unexamined, and diseases ran unchecked. I doubt if anyone living in one of today's secular, developed democracies would willingly transport themselves to that earlier time.
What has changed? Not human nature. We are still individually and collectively capable of horrendous acts of intolerance, violence and superstition. No, what has changed is the conceptual framework within which increasing numbers of us choose to live our lives:
Reason and empiricism replace authority, tradition and revelation as the basis for reliable knowledge of the world. The scientific way of knowing is respected and supported.
All men and women are equally endowed with the right to life, liberty and the pursuit of happiness, regardless of race, ethnicity, or religion.
Government derives from the consent of the governed, not divine right, religious precept or armed might.
Simple principles. Not always adhered to and easily perverted, but widely embraced. The philosophical articulation and widespread adoption of these principles has a name. It is called the Enlightenment.