But I got a great deal else from the experience. I learned to pitch a tent and sleep beneath the stars. For a brief, proud period I was slender and fit. I gained a profound respect for the wilderness and nature and the benign dark power of woods. I understand now, in a way I never did before, the colossal scale of the world. I found patience and fortitude that I didn't know I had. I discovered an America that millions of people scarcely know exists. I made a friend. I came home.

From an evolutionary point of view, sex is really just a reward mechanism to encourage us to pass on our genetic material.

Geologists are never at a loss for paperweights.

The real problem you get with humour is that you only have so many kinds of jokes within you, and you mine that vein a lot. This isn't just common to me; it's anybody who's funny.

Very little of what America does is actually bad, and I don't think it ever does anything anywhere that is intentionally bad. I mean, sometimes we make mistakes and bad judgments and kind of back the wrong regimes and things, but by and large what America does is really good.

I really enjoy going to a library and spending the day doing research - to me that is the most pleasurable part of writing the science book.

[The Royal Society] is quite simply the voice of science in Britain. It is intellectually rigorous, not afraid to be outspoken on controversial issues such as climate change, but it is not aggressively secular either, insisting on a single view of the world. In fact, there are plenty of eminent scientists - Robert Winston, for instance - who are also men of faith.