At teenage parties he was always wandering into the garden, sitting on a bench in the dark . . . staring up at the constellations and pondering all those big questions about the existence of God and the nature of evil and the mystery of death, questions which seemed more important than anything else in the would until a few years passed and some real questions had been dumped into your lap, like how to earn a living, and why people fell in and out of love, and how long you could carry on smoking and then give up without getting lung cancer.

I knew there was a story; once you find a dog with a fork through it, you know there's a story there.

I better make the plot good. I wanted to make it grip people on the first page and have a big turning point in the middle, as there is, and construct the whole thing like a bit of a roller coaster ride...

And I know I can do this because I went to London on my own, and because I solved the mystery…and I was brave and I wrote a book and that means I can do anything.

And it occurred to him that there were two parts to being a better person. One part was thinking about other people. The other part was not giving a toss what other people thought.

And this shows that people want to be stupid and they do not want to know the truth. And it shows that something called Occam's razor is true. And Occam's razor is not a razor that men shave with but a Law, and it says: Entia non sunt multiplicanda praeter necessitatem. Which is Latin and it means: No more things should be presumed to exist than are absolutely necessary. Which means that a murder victim is usually killed by someone known to them and fairies are made out of paper and you can't talk to someone who is dead.

If you enjoy math and you write novels, it's very rare that you'll get a chance to put your math into a novel. I leapt at the chance.