I have lived much of my life among molecules. They are good company. I tell my students to try to know molecules, so well that when they have some question involving molecules, they can ask themselves, What would I do if I were that molecule? I tell them, Try to feel like a molecule; and if you work hard, who knows? Some day you may get to feel like a big molecule!

We are the products of editing, rather than of authorship.

The great questions are those an intelligent child asks and, getting no answers, stops asking.

Our challenge is to give what account we can of what becomes of life in the solar system, this corner of the universe that is our home; and, most of all, what becomes of men-all men, of all nations, colors, and creeds. This has become one world, a world for all men. It is only such a world that can now offer us life, and the chance to go on.

When you have no experience of pain, it is rather hard to experience joy.

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.

We are living in a world in which all wars are wars of defense.