“The biggest mistake we can make is to think that we've figured the whole thing out. The people I know who are the greatest skeptics, who are least certain about how the world and the universe works, are also the most intelligent.... Absolute certainty is only for stupid people. It requires a certain intelligence for us to realize how little we actually know.”

“Our aim as scientists is objective truth; more truth, more interesting truth, more intelligible truth. We cannot reasonably aim at certainty. Once we realize that human knowledge is fallible, we realize also that we can never be completely certain that we have not made a mistake.”

“You are far too cynical for someone your age.""Well people are disappointing!" Thorn said."Yes, but they are also complicated. I would wager there is something about him you do not know. It is the only thing we can ever say about people with absolute certainty: that we don't know the whole story.”

“In fact, as I get older, I begin to feel that actually what we need more in the world is doubt; more skepticism, less crazed certainty. . . . People who know the answer and are going to impose it on everybody else, I think, are terrifying people.”

“While I wasn't certain how I felt about spiritualists, I was certain enough about the type of people who were drawn to them. Only people unhappy in the present seek to know the future.”

“A stupid person can make only certain, limited types of errors; the mistakes open to a clever fellow are far broader. But to the one who knows how smart he is compared to everyone else, the possibilities for true idiocy are boundless.”