This planet seems to be in such sorry shape. And I can't ever think about the rest of the universe without coming back home and thinking what the implications for life here would be if we were to really have some definitive proof of extraterrestrial life.

I found that it was easiest to convey the information in the context of the life of the scientist or in the context of our own personal experience, and there was no idea that was too complicated that couldn't be explained clearly and directly.

Ten long trips around the sun since I last saw that smile, but only joy and thankfulness that on a tiny world in the vastness, for a couple of moments in the immensity of time, we were one.

Science has the cold facts, but lacks religion's social organization and ability to inspire that moves people to act.

Carl took on the military-industrial complex. He campaigned around the world for an end to the production of weapons of mass destruction. To him it was a perversion of science.

A lot of people have this ego need that makes them want to believe that Earth is the center of the universe and humans are the most important species, the supreme expression of creation.

I remember that one time Carl Sagan was giving a talk, and he spelled out, in a kind of withering succession, these great theories of demotion that science has dealt us, all of the ways in which science is telling us we are not who we would like to believe we are. At the end of it, a young man came up to him and he said: "What do you give us in return? Now that you've taken everything from us? What meaning is left, if everything that I've been taught since I was a child turns out to be untrue?" Carl looked at him and said, Do something meaningful.