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.

Black bears rarely attack. But here's the thing. Sometimes they do. All bears are agile, cunning and immensely strong, and they are always hungry. If they want to kill you and eat you, they can, and pretty much whenever they want. That doesn't happen often, but - and here is the absolutely salient point - once would be enough.

I wish I could adjust my voice, but it's just what's happened to me. It's because I've lived abroad for a long time, and my wife is English and my kids all have English accents, and every voice I hear is English. I've never intentionally changed my accent at all.

If you go out on the Appalachian Trail, you have to bring so much more equipment - a tent, sleeping bag - but if you go hiking in England, or Europe, generally, towns and villages are near enough together at the end of the day you can always go to a nice little inn and have a hot bath and something to drink.

I can't fix the world. If you want to make a difference in life, you have to direct your energies in a focused way.

Human beings would split the atom and invent television, nylon, and instant coffee before they could figure out the age of their own planet.

There are three stages in scientific discovery. First, people deny that it is true, then they deny that it is important; finally they credit the wrong person.