A scientist lives with all reality. There is nothing better. To know reality is to accept it, and eventually to love it.

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.

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

Since we have had a history, men have pursued an ideal of immortality.

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.

Four elements, Hydrogen, carbon, oxygen and nitrogen, also provide an example of the astonishing togetherness of our universe. They make up the "organic" molecules that constitute living organisms on a planet, and the nuclei of these same elements interact to generate the light of its star. Then the organisms on the planet come to depend wholly on that starlight, as they must if life is to persist. So it is that all life on the Earth runs on sunlight. [Referring to photosynthesis]

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.