I already knew this, because I had been studying classical ballet for a long time. But a lot of people insisted on a wall between modern dance and ballet, that the two disciplines were totally separate, and if you did one, you couldn’t do the other. I’m beginning to think that walls are very unhealthy things.

Don’t write in public places. In the early 1990s I went to live in Paris. The usual writerly reasons: back then, if you were caught writing in a pub in England, you could get your head kicked in, whereas in Paris, dans les cafés . . . Since then I’ve developed an aversion to writing in public. I now think it should be done only in private, like any other lavatorial activity.

Some writers claim to extrude a book at an even rate like toothpaste from a tube, or to build a story like a wall, so many feet per day. They sit at their desk and knock off their word quota, then frisk into their leisured evening, preening themselves. This is so alien to me that it might be another trade entirely.

Sleep has to be, by far, the most underrated aspect of good health. I think sleeping less & working more is glorified. Life is like a marathon; if you run too fast and don't pace yourself, you can burn out, and you probably won't be able to finish strong.

Of course, the most rewarding part is the "Aha" moment, the excitement of discovery and enjoyment of understanding something new, the feeling of being on top of a hill, and having a clear view. But most of the time, doing mathematics for me is like being on a long hike with no trail and no end in sight! I find discussing mathematics with colleagues of different backgrounds one of the most productive ways of making progress.