At the foot of the mountain, the park ended and suddenly all was squalor again. I was once more struck by this strange compartmentalization that goes on in America -- a belief that no commercial activities must be allowed inside the park, but permitting unrestrained development outside, even though the landscape there may be just as outstanding. America has never quite grasped that you can live in a place without making it ugly, that beauty doesn't have to be confined behind fences, as if a national park were a sort of zoo for nature.

The English invented cricket to make other human endeavors look interesting.

And I find chopsticks frankly distressing. Am I alone in thinking it odd that a people ingenious enough to invent paper, gunpowder, kites and any number of other useful objects, and who have a noble history extending back 3,000 years haven't yet worked out that a pair of knitting needles is no way to capture food?

I understand cricket - what's going on, the scoring - but I can't understand why.

I see litter as part of a long continuum of anti-social behaviour.

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.

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.