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.

Arguments from authority carry little weight – authorities have made mistakes in the past. They will do so again in the future. Perhaps a better way to say it is that in science there are no authorities; at most, there are experts.

We are the custodians of life's meaning.

I set before you two ways: You can use your technology to destroy yourselves or to carry you to the planets and the stars. It's up to you.

In science it often happens that scientists say, "You know that's a really good argument; my position is mistaken..."

Science is a way of thinking much more than it is a body of knowledge.

We are the only species on the planet, so far as we know, to have invented a communal memory stored neither in our genes nor in our brains. The warehouse of this memory is called the library