To be alone is the fate of all great minds — a fate deplored at times, but still always chosen as the less grievous of two evils. - Arthur Schopenhauer

There is only one inborn error, and that is the notion that we exist in order to be happy... So long as we persist in this inborn error... the world seems to us full of contradictions. For at every step, in things great and small, we are bound to experience that the world and life are certainly not arranged for the purpose of maintaining a happy existence... hence the countenances of almost all elderly persons wear the expression of what is called disappointment.

Thus also every keen pleasure is an error and an illusion, for no attained wish can give lasting satisfaction.

For the more a man has in himself, the less he will want from other people, — the less, indeed, other people can be to him. This is why a high degree of intellect tends to make a man unsocial.