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.

A book is made from a tree. It is an assemblage of flat, flexible parts (still called "leaves") imprinted with dark pigmented squiggles. One glance at it and you hear the voice of another person, perhaps someone dead for thousands of years. Across the millennia, the author is speaking, clearly and silently, inside your head, directly to you. Writing is perhaps the greatest of human inventions, binding together people, citizens of distant epochs, who never knew one another. Books break the shackles of time ― proof that humans can work magic.

The difference between physics and metaphysics is not that the practitioners of one are smarter than the practitioners of the other. The difference is that the metaphysicist has no laboratory.

There is perhaps no better a demonstration of the folly of human conceits than this distant image of our tiny world.

What began in deadly competition has helped us to see that global cooperation is the essential precondition for our survival. Travel is broadening. It's time to hit the road again.

The gears of poverty, ignorance, hopelessness and low self-esteem interact to create a kind of perpetual failure machine that grinds down dreams from generation to generation. We all bear the cost of keeping it running. Illiteracy is its linchpin.

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.