Colonization means potential immortality for the human genus. Man's safety on Earth was never great, and it dwindles hourly. Disarmament, even world government, will not guarantee survival in an age when population presses natural resources to the limit and when the knowledge of how to work mischief on a planetary scale is ever more widely diffused among peoples who may grow ever more desperate.

Heaven is not as narrowly literal-minded as hell.

Will none wipe the sneer off the face of the cosmos?

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

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.

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.

The fish that first ventured ashore had considerable practical problems.