No doubt, the most challenging class of questions in science is the origin of things.

For centuries, epilepsy was the exact expectation of someone being possessed by the Devil. There was no better explanation, and it allows you to admit the existence of the Devil. If there's a Devil, that mean's there's a God.

Where did the concept of "without borders" come from? No one had that concept until you saw Earth from space, illustrated not by a mapmaker who's color-coding political boundaries; it's illustrated by nature itself and there's land, there's ocean, there's atmosphere.

He invited people to sign a petition that demanded either strict control of, or a total ban on, dihydrogen monoxide.... Yes, 86 percent of the passersby voted to ban water (H2O) from the environment. Maybe that's what really happened to all the water on Mars.

While the Copernican principle comes with no guarantees that it will forever guide us to cosmic truths, it's worked quite well so far: not only is Earth not in the center of the solar system, but the solar system is not in the center of the Milky Way galaxy, the Milky Way galaxy is not in the center of the universe, and it may come to pass that our universe is just one of many that comprise a multiverse. And in case you're one of those people who thinks that the edge may be a special place, we are not at the edge of anything either.

It is astonishing to realize that until Galileo performed his experiments on the acceleration of gravity in the early seventeenth century, nobody questioned Aristotle's falling balls. Nobody said, Show Me!

In science, if you don't do it, somebody else will. Whereas in art, if Beethoven didn't compose the 'Ninth Symphony,' no one else before or after is going to compose the 'Ninth Symphony' that he composed; no one else is going to paint 'Starry Night' by van Gogh.