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.

The fish that first ventured ashore had considerable practical problems.

At each stage...entirely new laws, concepts and generalizations are necessary, requiring inspiration and creativity to just as great a degree as in the previous one.

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.

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

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.

In my considered opinion, the profit to be made by permanent settlement in space is nothing less than the survival of industrial civilization, and therefore the survival of nearly the entire human race, along with such amenities as peace, freedom, enough to eat, and the chance to reach a high age in good health.