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

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.

There are some ideas so stupid that only intellectuals can believe in them, particularly left-wing intellectuals.

The fish that first ventured ashore had considerable practical problems.

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.

Heaven is not as narrowly literal-minded as hell.