Evolution advances, not by a priori design, but by the selection of what works best out of whatever choices offer. We are the products of editing, rather than of authorship.

Every creature alive on the earth today represents an unbroken line of life that stretches back to the first primitive organism to appear on this planet; and that is about three billion years.

There's life all over this universe, but the only life in the solar system is on earth, and in the whole universe we are the only men.

A peacetime draft is the most un-American thing I know.

If the germ plasm wants to swim in the ocean, it makes itself a fish; if the germ plasm wants to fly in the air, it makes itself a bird. If it wants to go to Harvard, it makes itself a man. The strangest thing of all is that the germ plasm that we carry around within us has done all those things. There was a time, hundreds of millions of years ago, when it was making fish. Then ... amphibia ... reptiles ... mammals, and now it's making men.

Science goes from question to question; big questions, and little, tentative answers. The questions as they age grow ever broader, the answers are seen to be more limited.

Nuclear weapons offer us nothing but a balance of terror, and a balance of terror is still terror.