"Isn't it sad to go to your grave without ever wondering why you were born? Who, with such a thought, would not spring from bed, eager to resume discovering the world and rejoicing to be part of it?"

"For the first half of geological time our ancestors were bacteria. Most creatures still are bacteria, and each one of our trillions of cells is a colony of bacteria."

"We are all atheists about most of the gods that societies have ever believed in. Some of us just go one god further."

"Intelligent life on a planet comes of age when it first works out the reason for its own existence."

"Time travel used to be thought of as just science fiction, but Einstein's general theory of relativity allows for the possibility that we could warp space-time so much that you could go off in a rocket and return before you set out."

"Everything in the universe has a purpose. Indeed, the invisible intelligence that flows through everything in a purposeful fashion is also flowing through you."

"Science reckons many prophets, but there is not even a promise of a Messiah."

"I don't read 'chick lit,' fantasy or science fiction but I'll give any book a chance if it's lying there and I've got half an hour to kill."