Roman Polanski actually said as much to me once. He had his head in his hands, and I said, "Roman, I've got to tell you, as an actor, seeing the director with his head in his hands... Look, I really want to do what you want me to do." And he went away and he came back, having obviously thought about what I said. And he said, "When my head is in my hands, I'm closing my eyes and trying to remember what I saw in my head, before any of the stuff."

It was fine when I was single and childless. Carrying the responsibility of screwing up your kids at the same time is huge. I remember when I got Peter Pan, and I told my mom and dad and my friends I was leaving - again, I was cast way late on - in the next two days to go to Australia for four months, and they all went "Bye! See you in four months!" But no one said "We need you," and I really knew that it was time to think about someone else for a change.

I had the best teacher in the business. Kevin Costner was my teacher. I was acting opposite him and he was directing me. The way he directed me, for which I am eternally grateful, is he would watch the scene back on the monitor, which is sort of considered unfashionable - you're not meant to watch yourself. But he was like, "Come around. Watch this. See there, you're doing a great reaction, but you're doing it out of frame." That was exactly what I needed. I learned how to act on film from him.

Ewan McGregor and I said this to each other after we saw The Ghost Writer. Every time Roman Polanski did a "No, no, no!," he was right. It was really as if a sculptor was asked to sculpt the embodiment of despair - that was the attitude he would strike. But as with every sort of inspiring teacher you ever had who was strict and scary, when you get it right, the sun comes out, and it's worth it.

We had an ancient Russian acting coach at my drama school who said the worst offense you could commit was to let your subtext show. That is the point of acting, is to be saying one thing and not be allowed by society or your predicament to show what you're really feeling. In a way, I think that's why the therapy generation has killed script writing, because all you ever get is people going, "Hi, I'm feeling really angry right now."

When the Hollywood thing happened, I thought at some point I'd get to the front of the queue: 'Yes, hello, I'd like to play that role.' But you don't. You just join a different queue.

My parents taught me everything and set me up for life. I owe to them all the things I'm passionate about: music, art, the people I love, my career and family life, the fact that I have children and the way that I raise them.