I am an optimist. Anyone interested in the future has to be otherwise he would simply shoot himself.

One of the great tragedies of mankind is that morality has been hijacked by religion.

Any technology distinguishable from magic is insufficiently advanced.

In this universe the night was falling; the shadows were lengthening towards an east that would not know another dawn. But elsewhere the stars were still young and the light of morning lingered; and along the path he once had followed, Man would one day go again.

Sometimes I think we're alone in the universe, and sometimes I think we're not. In either case the idea is quite staggering.

Isn't killing people in the name of God a pretty good definition of insanity?

It is not easy to see how the more extreme forms of nationalism can long survive when men have seen the Earth in its true perspective as a single small globe against the stars.