Better a life like a falling star, brief bright across the dark, than the long, long waiting of the immortals, loveless and cheerlessly wise.

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

The single definition of government I've ever seen that makes sense is that it's the organization which claims the right to kill people who won't do what it wants.

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

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.

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.

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