Charles Darwin was often so impressed by 'the extreme difficulty, or rather impossibility, of conceiving this immense and wonderful universe, including man … as the result of blind chance or necessity' that he felt the need for an intelligent first cause - or so he muses. He might be thought a theist. Except that he also appreciated that human beings are hardly equipped to decide on such matters: faculties which 'have been developed from a mind as low as that possessed by the lowest animals' cannot be fully trusted when they draw 'such grand conclusions'. Socrates could not have put it better.

In short, he was agnostic, as Mary Midgley shows in a typically penetrating article. What is so interesting about Darwin's internal discussion is precisely that: he realised that the primary site for the debate about the relationship between science and religion is inside each of us - as Midgley continues, 'conflicts, not between different parties in the world but within each one of us, between different parts of our own nature'.