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.

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

Death seems to have been a rather late invention in evolution. One can go a long way in evolution before encountering an authentic corpse.

We've committed many war crimes in Vietnam - but I'll tell you something interesting about that. We were committing war crimes in World War II, before the Nuremberg trials were held and the principle of war crimes was stated.

The Vietnamese have a secret weapon. It's their willingness to die beyond our willingness to kill. In effect, they've been saying, You can kill us, but you'll have to kill a lot of us; you may have to kill all of us. And, thank heaven, we are not yet ready to do that.

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

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.