All of us cherish our beliefs. They are, to a degree, self-defining. When someone comes along who challenges our belief system as insufficiently well-based - or who, like Socrates, merely asks embarrassing questions that we haven't thought of, or demonstrates that we've swept key underlying assumptions under the rug - it becomes much more than a search for knowledge. It feels like a personal assault.

Absolute certainty will always elude us. We will always be mired in error. The most each generation can hope for is to reduce the error. . . .

Scientists constantly get clobbered with the idea that we spent 27 billion dollars on the Apollo programs, and are asked "What more do you want?" We didn't spend it; it was done for political reasons. ... Apollo was a response to the Bay of Pigs fiasco and to the successful orbital flight of Yuri Gagarin. President Kennedy's objective was not to find out the origin of the moon by the end of the decade; rather it was to put a man on the moon and bring him back, and we did that.

Think of how many religions attempt to validate themselves with prophecy. Think of how many people rely on these prophecies, however vague, however unfulfilled, to support or prop up their beliefs. Yet has there ever been a religion with the prophetic accuracy and reliability of science? ... No other human institution comes close.

For all our conceits about being the center of the universe, we live in a routine planet of a humdrum star stuck away in an obscure corner ... on an unexceptional galaxy which is one of about 100 billion galaxies. ... That is the fundamental fact of the universe we inhabit, and it is very good for us to understand that.

There is a lurking fear that some things are not “meant" to be known, that some inquiries are too dangerous for human beings to make.

We are made of starstuff.