I sometimes think that the universe is a machine designed for the perpetual astonishment of astronomers.

One of the great tragedies of mankind is that morality has been hijacked by religion.

We have to abandon the idea that schooling is something restricted to youth. How can it be, in a world where half the things a man knows at 20 are no longer true at 40 - and half the things he knows at 40 hadn't been discovered when he was 20?

. . . the newspapers of Utopia, he had long ago decided, would be terribly dull.

Many, and some of the most pressing, of our terrestrial problems can be solved only by going into space. Long before it was a vanishing commodity, the wilderness as the preservation of the world was proclaimed by Thoreau. In the new wilderness of the Solar System may lie the future preservation of mankind.

Before the current decade ends, fee-paying passengers will be experiencing suborbital flights aboard privately funded vehicles. . . . It won't be too long before bright young men and women set their eyes on careers in Earth orbit and say: "I want to work 200 kilometers from home-straight up!"

The numbers of distinct human societies or nations, when our race is twice its present age, may be far greater than the total number of all the men who have ever lived up to the present time.