Except in pure mathematics, nothing is known for certain (although much is certainly false).

As the ancient myth makers knew, we are children equally of the earth and the sky.

When you look more generally at life on Earth, you find that it is all the same kind of life. There are not many different kinds; there's only one kind. It uses about fifty fundamental biological building blocks, organic molecules.

For a long time the human instinct to understand was thwarted by facile religious explanations.

Books tap the wisdom of our species -- the greatest minds, the best teachers -- from all over the world and from all our history. And they're patient.

It does no harm to the romance of the sunset to know a little bit about it.

What counts is not what sounds plausible, not what we would like to believe, not what one or two witnesses claim, but only what is supported by hard evidence rigorously and skeptically examined. Extraordinary claims require extraordinary evidence.