It means nothing to be open to a proposition we don't understand.

As agonizing a disease as cancer is, I do not think it can be said that our civilization is threatened by it. ... But a very plausible case can be made that our civilization is fundamentally threatened by the lack of adequate fertility control. Exponential increases of population will dominate any arithmetic increases, even those brought about by heroic technological initiatives, in the availability of food and resources, as Malthus long ago realized.

Science is far from a perfect instrument of knowledge. It's just the best we have.

Books are key to understanding the world and participating in a democratic society.

The reappearance of the crescent moon after the new moon; the return of the Sun after a total eclipse, the rising of the Sun in the morning after its troublesome absence at night were noted by people around the world; these phenomena spoke to our ancestors of the possibility of surviving death. Up there in the skies was also a metaphor of immortality.

The way to find out about our place in the universe is by examining the universe and by examining ourselves - without preconceptions, with as unbiased a mind as we can muster.

When permitted to listen to alternative opinions and engage in substantive debate, people have been known to change their minds. It can happen.