Curiosity and the urge to solve problems are the emotional hallmarks of our species.

You're an interesting species, an interesting mix. You're capable of such beautiful dreams and such horrible nightmares. You feel so lost, so cut off, so alone, only you're not. See, in all our searching, the only thing we've found that makes the emptiness bearable is each other.

The notion that science and spirituality are somehow mutually exclusive does a disservice to both.

If you wish to make an apple pie from scratch, you must first invent the universe.

We are rare and precious because we are alive, because we can think as well as we can. We are privileged to influence and perhaps control our future. I believe we have an obligation to fight for life on Earth - not just for ourselves, but for all those, humans and others, who came before us, and to whom we are beholden, and for all those who, if we are wise enough, will come after.

After the earth dies, some 5 billion years from now, after it's burned to a crisp, or even swallowed by the Sun, there will be other worlds and stars and galaxies coming into being - and they will know nothing of a place once called Earth.

All of the books in the world contain no more information than is broadcast as video in a single large American city in a single year. Not all bits have equal value.