Register now or log in to join your professional community.
Political, religious, showbiz, good, bad whatever!
All of them..
This is something I've considered a few times, though never really done a great deal of research into. I think the one thing that has had the greatest impact on the world is the concept of the scientific method. The idea that things are explainable, explanations can and should be rigorously tested and superstition and magic be forsworn in favor of evidence-based theories is what makes a society modern.