This oak tree and me, we're made of the same stuff.

Advances in medicine and agriculture have saved vastly more lives than have been lost in all the wars in history.

I think if we ever reach the point where we think we thoroughly understand who we are and where we came from, we will have failed.

Absolute certainty will always elude us. We will always be mired in error. The most each generation can hope for is to reduce the error. . . .

The cure for a fallacious argument is a better argument, not the suppression of ideas.

Which aspects of our nature will prevail is uncertain, particularly when our visions and prospects are bound to one small part of the small planet Earth. But up there in the Cosmos an inescapable perspective awaits.

We have also arranged things so that almost no one understands science and technology. This is a prescription for disaster. We might get away with it for a while, but sooner or later this combustible mixture of ignorance and power is going to blow up in our faces.