They are in you and me; they created us, body and mind; and their preservation is the ultimate rationale for our existence. They have come a long way, those replicators. Now they go by the name of genes, and we are their survival machines.

We cannot prove that there is no God, but we can safely conclude the He is very, very improbable indeed.

The important thing to remember about mathematics is not to be frightened

Yes, testosterone-sodden young men too unattractive to get a woman in this world might be desperate enough to go for 72 private virgins in the next.

You can never be absolutely certain that anything doesn't exist. But you can show that it's unlikely.

The take-home message is that we should blame religion itself, not religious extremism - as though that were some kind of terrible perversion of real, decent religion. Voltaire got it right long ago: 'Those who can make you believe absurdities can make you commit atrocities.' So did Bertrand Russell: 'Many people would sooner die than think. In fact they do.

I think we certainly benefit from social institutions which encourage us towards moral behavior. It's very important to have law. It's very important to have a moral education.