The most merciful thing in the world, I think, is the inability of the human mind to correlate all its contents. We live on a placid island of ignorance in the midst of black seas of infinity, and it was not meant that we should voyage far. The sciences, each straining in its own direction, have hitherto harmed us little; but some day the piecing together of dissociated knowledge will open up such terrifying vistas of reality, and of our frightful position therein, that we shall either go mad from the revelation or flee from the light into the peace and safety of a new dark age.
People tend to think of a dark age as a discrete point in history. It was a time of upheaval and despair. Societies across the world were reeling from the decline of a great power that once brought peace and stability. It was something that was overcome, long ago in the distant past, forever banished to the dim memory of historians.
Nothing could be farther from the truth. The causes behind all dark ages are still present. They can never leave humanity. A dark age is the standard state of a society. Chaos can only be subdued through determination and will.