Science is based on experiment, on a willingness to challenge old dogma, on an openness to see the universe as it really is. Accordingly, science sometimes requires courage - at the very least the courage to question the conventional wisdom.

What an astonishing thing a book is. It’s a flat object made from a tree with flexible parts on which are imprinted lots of funny dark squiggles. But one glance at it and you’re inside the mind of another person, maybe somebody dead for thousands of years. ... Books break the shackles of time. A book is proof that humans are capable of working magic.

I worry that, especially as the Millennium edges nearer, pseudo-science and superstition will seem year by year more tempting, the siren song of unreason more sonorous and attractive.

In all our searching, the only thing we've found that makes the emptiness bearable is each other.

Our intelligence is imperfect, surely, and newly arisen; the ease with which it can be sweet-talked, overwhelmed, or subverted by other hardwired propensities - sometimes themselves disguised as the cool light of reason - is worrisome.

Except for fools and madmen, everyone knows that nuclear war would he an unprecedented human catastrophe.

Our loyalties are to the species and the planet. We speak for Earth. Our obligation to survive is owed not just to ourselves but also to that Cosmos, ancient and vast, from which we spring.