So much American science fiction is parochial - not as true now as it was years ago, but the assumption is one culture in the future, more or less like ours, and with the same ideals, the same notions of how to do things, just bigger and flashier technology. Well, you know darn well it doesn't work that way.

If we knew exactly what to expect throughout the Solar System, we would have no reason to explore it.

Give fear no hold on you. Keep sinews loose and senses open, ready at every instant to flow with the rush of action.

In Harvest of Stars, there is this notion, not original with me of course, that it will become possible to download at least the basic aspects of a human personality into a machine program.

I wrote the first book, Harvest of Stars, and as I was writing it, I saw that certain implications had barely been touched on... It's perfectly obvious that two completely revolutionary things are going on, with cybernetics, and biological science.

He had seen too much of the cosmos to have any great faith in man's ability to understand it.

A fanatic is a man who, when he's lost sight of his purpose, redoubles his effort.