The nuclear arms race is like two sworn enemies standing waist deep in gasoline, one with three matches, the other with five.

Advances in medicine and agriculture have saved vastly more lives than have been lost in all the wars in history.

The Platonists and their Christian successors held the peculiar notion that the Earth was tainted and somehow nasty, while the heavens were perfect and divine. The fundamental idea that the Earth is a planet, that we are citizens of the Universe, was rejected and forgotten.

It is clear that the nations of the world now can only rise and fall together. It is not a question of one nation winning at the expense of another. We must all help one another or all perish together.

All civilizations become either spacefaring or extinct.

If I finish a book a week, I will read only a few thousand books in my lifetime, about a tenth of a percent of the contents of the greatest libraries of our time. The trick is to know which books to read.

There is in this Universe much of what seems to be design.