All the suffering that humanity ever knew can be traced to the one fact...

Every human being lived behind an impenetrable wall of chocking mist within which no other but he existed. Ocassionally there were dim signals from deep within the cavern in which another man was located - so that each might grope towards the other. Yet because they did not know one another, and could not understand one another, and dared not trust one another, and felt from infancy the terrors and insecurity of that ultimate isolation - there was the hunted fear of man for man, the savage rapacity of man towards man.

Isaac Asimov