Hunters will tell you that a moose is a wily and ferocious forest creature. Nonsense. A moose is a cow drawn by a three-year-old.

My favourite fellow of the Royal Society is the Reverend Thomas Bayes, an obscure 18th-century Kent clergyman and a brilliant mathematician who devised a complex equation known as the Bayes theorem, which can be used to work out probability distributions. It had no practical application in his lifetime, but today, thanks to computers, is routinely used in the modelling of climate change, astrophysics and stock-market analysis.

I love the feeling of being anonymous in a city I've never been before.

Consider the Lichen. Lichens are just about the hardiest visible organisms on Earth, but the least ambitious.

We used to build civilizations. Now we build shopping malls.

If this book has a lesson, it is that we are awfully lucky to be here-and by 'we' I mean every living thing. To attain any kind of life in this universe of ours appears to be quite an achievement. As humans we are doubly lucky, of course: We enjoy not only the privilege of existence but also the singular ability to appreciate it and even, in a multitude of ways, to make it better. It is a talent we have only barely begun to grasp.

I don't want to go and start trying to make jokes in places like India, Tanzania or Iraq. Afghanistan is not a funny place.