As you lecture, you keep watching the faces, and information keeps coming back to you all the time.

About two million years ago, man appeared. He has become the dominant species on the earth. All other living things, animal and plant, live by his sufferance. He is the custodian of life on earth, and in the solar system. It's a big responsibility.

It's not good enough to give it tender, loving care, to supply it with breakfast foods, to buy it expensive educations. Those things don't mean anything unless this generation has a future. And we're not sure that it does.

I can conceive of no nightmare so terrifying as establishing communication with a so-called superior (or, if you wish, advanced) technology in outer space.

It would be a poor thing to be an atom in a universe without physicists, and physicists are made of atoms. A physicist is an atom's way of knowing about atoms.

A physicist is an atom's way of knowing about atoms.

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.