“Another principle that I believe can be justified by scientific evidence so far is that nobody is going to emigrate from this planet not ever....It will be far cheaper, and entail no risk to human life, to explore space with robots. The technology is already well along....the real thrill will be in learning in detail what is out there...It is an especially dangerous delusion if we see emigration into space as a solution to be taken when we have used up this planet....Earth, by the twenty-second century, can be turned, if we so wish, into a permanent paradise for human beings...”

“A lifetime can be spent in a Magellanic voyage around the trunk of a single tree.”

“If there is danger in the human trajectory, it is not so much in the survival of our own species as in the fulfillment of the ultimate irony of organic evolution: that in the instant of achieving self-understanding through the mind of man, life has doomed its most beautiful creations.”

“Real scientists do not take vacations. They take field trips...”

“And we really should be considering the moral implications of what we're doing. What kind of a species are we that we treat the rest of life so cheaply? There are those who think that's the destiny of Earth: We arrived, we're humanizing the Earth, and it will be the destiny of Earth for us to wipe humans out and most of the rest of biodiversity. But I think the great majority of thoughtful people consider that a morally wrong position to take, and a very dangerous one.”

“[Scientific humanism is] the only worldview compatible with science's growing knowledge of the real world and the laws of nature.”

“You teach me, I forget. You show me, I remember. You involve me, I understand.”

“The best way to live in this real world is to free ourselves of demons and tribal gods.”

“They travel long distances to stroll along the seashore, for reasons they can't put into words.”

“If all mankind were to disappear, the world would regenerate back to the rich state of equilibrium that existed ten thousand years ago. If insects were to vanish, the environment would collapse into chaos.”

“Humanity is a biological species, living in a biological environment, because like all species, we are exquisitely adapted in everything: from our behavior, to our genetics, to our physiology, to that particular environment in which we live. The earth is our home. Unless we preserve the rest of life, as a sacred duty, we will be endangering ourselves by destroying the home in which we evolved, and on which we completely depend.”