No one knows, incidentally, why Australia's spiders are so extravagantly toxic; capturing small insects and injecting them with enough poison to drop a horse would appear to be the most literal case of overkill. Still, it does mean that everyone gives them lots of space.

The upshot of all this is that we live in a universe whose age we can't quite compute, surrounded by stars whose distances we don't altogether know, filled with matter we can't identify, operating in conformance with physical laws whose properties we don’t truly understand.

Disassemble the cells of a sponge (by passing them through a sieve, for instance), then dump them into a solution, and they will find their way back together and build themselves into a sponge again. You can do this to them over and over, and they will doggedly reassemble because, like you and me and every other living thing, they have one overwhelming impulse: to continue to be.

But that's the glory of foreign travel, as far as I am concerned. I don't want to know what people are talking about. I can't think of anything that excites a greater sense of childlike wonder than to be in a country where you are ignorant of almost everything. Suddenly you are five years old again. You can't read anything, you have only the most rudimentary sense of how things work, you can't even reliably cross a street without endangering your life. Your whole existence becomes a series of interesting guesses.

I don't know whether I'm misanthropic. It seems to me I'm constantly disappointed. I'm very easily disappointed.

Hardly anyone ever leaves. This is because Des Moines is the most powerful hypnotic known to man. Outside town there is a big sign that says, WELCOME TO DES MOINES. THIS IS WHAT DEATH IS LIKE. There isn't really. I just made that up. But the place does get a grip on you.

It's hard not to be kind of pessimistic about human beings generally, because we do tend to mess things up. If you just look at the history of extinctions, we've killed off an awful lot of animals - and I don't think we're doing a very good job of looking after the planet.