Snowpiercer has both [optimistic and pessimistic]. It was essentially optimistic. The most pessimistic was my part, because of his knowledge. He knows how it started. The status quo, he knows, has to be maintained, otherwise there is no chance. He knows that this revolution is completely understandable and is also commendable. He also knows the negatives. In the end, that's not a very positive position to be in.

My fathers a clergyman, and he was in the mission field for a certain amount of time in British Honduras, which is now Belize.

The first film is everything you want to say and how you want to say it. Lots of directors will do that and do it really well, but the second film is not so easy.

A mathematician either has a feeling for equations and an understanding and delight in it, not only in the purity of it, but in its beauty as well. I don't think that's something that you learn at school. I think you can get better in mathematics on a school level, but when you're talking about being a mathematician, I think that's definitely a gift of genes or whatever, you know? Whatever your pool is.

Films don't take as long as people think. 'Harry Potter,' people always used to say, 'Well, my God, do you ever get any time to yourself?' I think I did, in 'Harry Potter,' over a 12 year period I did five days. So it's not exactly exhausting.

It's quite a dangerous career move to go wilfully on making films that may not find a distributor.

I'd say the film to avoid is a director's second film, particularly if his first film was a big success. The second film is where you've really needed to have learned something.