My parents were not scientists. They knew almost nothing about science. But in introducing me simultaneously to skepticism and to wonder, they taught me the two uneasily cohabiting modes of thought that are central to the scientific method.

In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion.

In the deepest sense the search for extraterrestrial intelligence is a search for ourselves.

Personally, I would be delighted if there were a life after death, especially if it permitted me to continue to learn about this world and others, if it gave me a chance to discover how history turns out.

If chimpanzees have consciousness, if they are capable of abstractions, do they not have what until now has been described as 'human rights'? How smart does a chimp have to be before killing him constitutes murder?

The price we pay for anticipation of the future is anxiety about it

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.