You can't even begin to understand biology, you can't understand life, unless you understand what it's all there for, how it arose - and that means evolution.

But, however many ways there may be of being alive, it is certain that there are vastly more ways of being dead, or rather not alive.

An atheist is just somebody who feels about Yahweh the way any decent Christian feels about Thor or Baal or the golden calf. We are all atheists about most of the gods that humanity has ever believed in. Some of us just go one god further.

Next time that somebody tells you something is true, why not say to them: 'What kind of evidence is there for that?' And if they can't give you a good answer, I hope you'll think very carefully before you believe a word they say.

If you look up at the Milky Way through the eyes of Carl Sagan, you get a feeling in your chest of something greater than yourself. And it is. But it's not supernatural.

Suppose that there's a gene that makes you gay if you were bottle-fed but that has some completely different effect if you were breast-fed. So in the days before bottles were invented that gene would not have manifested itself as gay behavior, but now that bottles are common it can do so.

One of the possible reasons why we might be good is that we're frightened, frightened of God. We want the reward in Heaven, we don't want to go to Hell. That would be an ignoble, ignominious reason for being good, and I think that if anybody was good to you just because they hoped for a heavenly reward, you wouldn't respect them, you'd probably give them a wide berth.