They absorb carbon monoxide and carbon dioxide and give out oxygen. What could be more desirable? And they look good in the bargain. Stop chopping down the rain forests and plant more saplings, and we're on our way.

Humanists recognize that it is only when people feel free to think for themselves, using reason as their guide, that they are best capable of developing values that succeed in satisfying human needs and serving human interests.

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.

You must keep sending work out; you must never let a manuscript do nothing but eat its head off in a drawer. You send that work out again and again, while you're working on another one. If you have talent, you will receive some measure of success - but only if you persist.

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.

To test a perfect theory with imperfect instruments did not impress the Greek philosophers as a valid way to gain knowledge.

All sorts of computer errors are now turning up. You'd be surprised to know the number of doctors who claim they are treating pregnant men.