Perhaps, in retrospect, there would be little motivation even for malevolent extraterrestrials to attack the Earth; perhaps, after a preliminary survey, they might decide it is more expedient just to be patient for a little while and wait for us to self-destruct.

In the deepest sense the search for extraterrestrial intelligence is a search for ourselves.

All civilizations become either spacefaring or extinct.

The brain is like a muscle. When it is in use we feel very good. Understanding is joyous.

I consider it an extremely dangerous doctrine, because the more likely we are to assume that the solution comes from the outside, the less likely we are to solve our problems ourselves.

Humans are very good at dreaming, although you'd never know it from your television.

At the extremes it is difficult to distinguish pseudoscience from rigid, doctrinaire religion.