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.

You have to learn to cut your cloth accordingly. But it seems to be a human weakness. Once you start making a lot of money, you just join in with everyone else. It's like the banks, and we've seen what happens there.

I think you can fan the flames, but I think in the same way that a mathematician is a mathematician - He's not taught to be a mathematician. He 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.

If you've got a great crew it's intense, but its quite short. 'The Elephant Man' was longer than most, for an independent film. That was a 14 week film. But it was because of the intrinsic difficulties. We had to invent a different way of filming, because the makeup was so long. A working day for me with a full makeup on was nineteen hours. So obviously you couldn't do that twice running.

Bong Joon-ho is enormously sensitive to performance. He knows what he needs to see and that's all he needs to shoot. He is so daring. We don't do that in the west. We shoot everything.

I mark a script like an exam, and I try not to do anything under 50 per cent. Similarly with the part. And also film is a peculiar thing, parts don't necessarily read in script form anything like as well as they can do when it comes to materialising.

I've spent a great deal of my life doing independent film, and that is partly because the subject matter interests me and partly because that is the basis of the film industry. That's where the film-makers come from, it's where they start and sometimes its where they should have stayed.