Unfortunately, in many cases, people who write science fiction violate the laws of nature, not because they want to make a point, but because they don't know what the laws of nature are.

After years of finding mathematics easy, I finally reached integral calculus and came up against a barrier. I realized that this was as far as I could go, and to this day I have never successfully gone beyond it in any but the most superficial way.

On Earth, we are unmanned by our longing for a pastoral past that never really existed; and that, if it had existed, could never exist again...on the Moon, there is no past to long for or dream about. There is no direction but forward.

The fundamentalists deny that evolution has taken place; they deny that the earth and the universe as a whole are more than a few thousand years old, and so on. There is ample scientific evidence that the fundamentalists are wrong in these matters, and that their notions of cosmogony have about as much basis in fact as the Tooth Fairy has.

Grip the nettle firmly and it will become a stick with which to beat your enemy.

With both people and computers on the job, computer error can be more quickly tracked down and corrected by people and, conversely, human error can be more quickly corrected by computers. What it amounts to is that nothing serious can happen unless human error and computer error take place simultaneously. And that hardly ever happens.

Nonsense! The most hopelessly stupid man is he who is not aware that he is wise.