What five books would I like to be remembered for? Well... Tau Zero, I like that one especially. It was somewhat of a tour de force, and I think it got across what I was trying for.

Two lives met across death and centuries. To ask what it meant is meaningless. There is no destiny. But sometimes there is bravery

I have yet to see any problem, however complicated, which, when you looked at it in the right way, did not become still more complicated.

It is a truism that the structure of a society is basically determined by its technology. Not in an absolute sense-there may be totally different cultures using identical tools-but the tools settle the possibilities; you can't have interstellar trade without spaceships. A race limited to a single planet, possessing a high knowledge of mechanics but with its basic machines of industry and war requiring a large capital investment, will inevitably tend toward collectivism under one name or another. Free enterprise needs elbow room.

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.

A fanatic's willingness to kill or be killed in the service of a cause cannot prove the rightness of that cause.

The fish that first ventured ashore had considerable practical problems.