I have made a discovery,' said Giskard, his voice carrying no shade of emotion. 'I have made it because, for the first time in my existence, I faced … - Isaac Asimov

Civilizations have always been pyramidal in structure. As one climbs toward the apex of the social edifice, there is increased leisure and increasing opportunity to pursue happiness. As one climbs, one finds also fewer and fewer people to enjoy this more and more. Invariably, there is a preponderance of the dispossessed. And remember this, no matter how well off the bottom layers of the pyramid might be on an absolute scale, they are always dispossessed in comparison with the apex.
So there is always social friction in ordinary human societies. The action of social revolution and the reaction of guarding against such revolution or combating it once it has begun are the causes of a great deal of the human misery with which history is permeated.

We're forever teetering on the brink of the unknowable, and trying to understand what can't be understood.

Celebro que los ingenieros no hayan inventado todavía el robot que pueda trabajar en la oscuridad total. Me horrorizaría encontrar siete robots en un pozo negro sin radiocomunicación, si no estuviesen "iluminados" como árboles de Navidad radiactivos.