Scientists make mistakes. Accordingly, it is the job of the scientist to recognize our weakness, to examine the widest range of opinions, to be ruthlessly self-critical. Science is a collective enterprise with the error-correction machinery often running smoothly.

If I finish a book a week, I will read only a few thousand books in my lifetime, about a tenth of a percent of the contents of the greatest libraries of our time. The trick is to know which books to read.

Religions are tough. Either they make no contentions which are subject to disproof or they quickly redesign doctrine after disproof. ... near the core of the religious experience is something remarkably resistant to rational inquiry.

A galaxy is composed of gas and dust and stars - billions upon billions of stars. Every star may be a sun to someone.

We wish to find the truth, no matter where it lies. But to find the truth we need imagination and skepticism both. We will not be afraid to speculate, but we will be careful to distinguish speculation from fact.

In college, in the early 1950s, I began to learn a little about how science works, the secrets of its great success, how rigorous the standards of evidence must be if we are really to know something is true, how many false starts and dead ends have plagued human thinking, how our biases can colour our interpretation of evidence, and how often belief systems widely held and supported by the political, religious and academic hierarchies turn out to be not just slightly in error, but grotesquely wrong.

And you are made of a hundred trillion cells. We are, each of us, a multitude.