If you are only skeptical, then no new ideas make it through to you. You become a crotchety old person convinced that nonsense is ruling the world. (There is, of course, much data to support you.) But every now and then, a new idea turns out to be on the mark, valid and wonderful. If you are too much in the habit of being skeptical about everything, you are going to miss or resent it, and either way you will be standing in the way of understanding and progress.

All of the rocky and metallic material we stand on, the iron in our blood, the calcium in our teeth, the carbon in our genes were produced billions of years ago in the interior of a red giant star. We are made of star stuff.

The fact that someone says something doesn't mean it's true. Doesn't mean they're lying, but it doesn't mean it's true.

I went to the librarian and asked for a book about stars.... And the answer was stunning. It was that the Sun was a star but really close. The stars were suns, but so far away they were just little points of light.... The scale of the universe suddenly opened up to me. It was a kind of religious experience. There was a magnificence to it, a grandeur, a scale which has never left me. Never ever left me.

If we are merely matter intricately assembled, is this really demeaning? If there's nothing here but atoms, does that make us less or does that make matter more?

We are at a crossroads in human history. Never before has there been a moment so simultaneously perilous and promising. We are the first species to have taken evolution into our own hands.

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