Any entity – no matter how many tentacles it has – has a soul. — Extraterrestrial life

"The quest for other, and better, forms of life, society, technology, ethics, and law may not reveal that they are actually elsewhere; but it may in the long run help us to make some of them actual on earth."

"Two possibilities exist: Either we are alone in the Universe or we are not. Both are equally terrifying."

"If, for example, tomorrow an expedition of Martians came to us here and one said ‘I want to be baptised!’, what would happen? Martians, right? Green, with long noses and big ears, like in children’s drawings? When the Lord shows us the way, who are we to say, ‘No, Lord, it is not prudent! No, lets do it this way’. Who are we to close doors?"

"Since, in the long run, every planetary society will be endangered by impacts from space, every surviving civilization is obliged to become spacefaring — not because of exploratory or romantic zeal, but for the most practical reason imaginable: staying alive."

"Do there exist many worlds, or is there but a single world? This is one of the most noble and exalted questions in the study of Nature."

"I would vote for Bach, all of Bach, streamed out into space, over and over again. We would be bragging of course."