At two-tenths the speed of light, dust and atoms might not do significant damage even in a voyage of 40 years, but the faster you go, the worse it is--space begins to become abrasive. When you begin to approach the speed of light, hydrogen atoms become cosmic-ray particles, and they will fry the crew. ...So 60,000 kilometers per second may be the practical speed limit for space travel.

The world of A.D. 2014 will have few routine jobs that cannot be done better by some machine than by any human being. Mankind will therefore have become largely a race of machine tenders.

If I am right, then (religious fundamentalists) will not go to Heaven, because there is no Heaven. If they are right, then they will not go to Heaven, because they are hypocrites.

There are no nations! There is only humanity. And if we don't come to understand that right soon, there will be no nations, because there will be no humanity.

There is no belief, however foolish, that will not gather its faithful adherents who will defend it to the death.

I have written 240 books on a wide variety of topics. . . . Some of it I based on education I received in my school, but most of it was backed by other ways of learning - chiefly in the books I obtained in the public library.

Boasts are wind and deeds are hard.