Hypatia, a student of science, was brutally murdered by a Christian mob c. 405 CE. From that point on the Dark Ages set it wherein truth was defined in Western Civilization by the Christian Bible. It was another ten and half centuries before Galileo ignited the spark of reality that became the Enlightenment where the realization set in that the Christian "truth" was misbegotten. From there humanity began an intellectual journey providing us with the actual truth, that humans are the outcome of a long, arduous evolution from single-celled creatures, that our world is a small planet in a small solar system among billions of solar systems in billions of galaxies, that in fact the primitive conceptions of life in the Christian Bible are based on ancient tales told to enhance the power of the priesthood class.
The Greeks also had their Enlightenment with remarkable advancement in mathematics, geometry, and physics. With Democritus, the Grecian Galileo, science was born. Euclid, Pythagoras, Thales, Archimedes, and many others built an amazing intellectual foundation for our understanding of the world around us. But all that came to an end with the burning of the Alexandrian Library, and the murder of Hypatia. That happened because of the social disorder that accompanied the collapse of the Roman Empire. And it is quite likely to happen again.
Then as now few people actually believed in the true reality around them. Surveys consistently find most people rejecting the evolution of life on this planet, and many more who believe that there'll be a second coming and that most people are going to hell, just as so many people at the time of the Greek scientists that Zeus or Jupiter ruled the heavens.
The immense knowledge of our universe, of mathematics, cosmology, physics, chemistry, is harbored in the minds of a small minority of people. As global warming brings about social disorder, the same kind that the Roman Empire found itself in, some new superstition will dominate. Maybe a version of Christianity, or more likely, some version of Islam. Even as I'm writing this, an army is taking over parts of Syria and Iraq with the intention of establishing a conservative form of Islam. This is just the beginning. The kinds of disorder that is bringing that about in the Middle East, will eventually spread to the rest of the world.
And the cost of that disorder will be the end of the Enlightenment, just as the Grecian Enlightenment ended with Hypatia. At some point someone or some group will be sacrificed to some god or gods, and it will be over. Probably not in my lifetime, but soon enough, my children or grandchildren will witness the triumph of superstition over truth. And how many centuries will pass before science is born again?