There are many hypotheses in physics of almost comparable brillance and elegance that have been rejected because they did not survive such a confrontation with experiment. In my view, the human condition would be greatly improved if such confrontations and willingness to reject hypotheses were a regular part of our social, political, economic, religious and cultural lives.
Carl SaganWhen you buy a used car, you kick the tires, you look at the odometer, you open up the hood. If you do not feel yourself an expert in automobile engines, you bring a friend who is. And you do this with something as unimportant as an automobile. But on the issues of the transcendent, of ethics, of morals, of the origins of the world, of the nature of human beings, on those issues should we not insist upon at least equally skeptical scrutiny?
Carl SaganWhat a splendid perspective contact with a profoundly different civilization might provide! In a cosmic setting vast and old beyond ordinary human understanding we are a little lonely, and we ponder the ultimate significance, if any, of our tiny but exquisite blue planet, the Earth.... In the deepest sense the search for extraterrestrial intelligence is a search for ourselves.
Carl SaganQuickly capping 363 oil well fires in a war zone is impossible. The fires would burn out of control until they put themselves out... The resulting soot might well stretch over all of South Asia... It could be carried around the world... [and] the consequences could be dire. Beneath such a pall sunlight would be dimmed, temperatures lowered and droughts more frequent. Spring and summer frosts may be expected... This endangerment of the food supplies... appears to be likely enough that it should affect the war plans.
Carl SaganWe seem, these days, much more willing to recognize the perils before us than we were even a decade ago. The newly recognized dangers threaten all of us, equally. No one can say how it will turn out down here. But this is also, we may note, the first time that a species has become able to journey to the planets and the stars. Sailors on a becalmed sea, we sense a stirring of the breeze.
Carl Sagan