I think we all have light and dark inside us 
Controversial actor Sean Penn's huge talent has sometimes been overshadowed by his wild antics off camera. Now, at 43, he is doing some of the best work of his life in 21 Grams, Alejandro González Iñárritu's towering follow-up to Amores Perros, and Clint Eastwood's Mystic River, for which he received his first Oscar. He will next be seen in The Assassination Of Richard Nixon.
This is only Alejandro González Iñárritu's second film. What drew you to work with him?
Directors like Alejandro come along very rarely, and you're very lucky if you stumble across one in your life as an actor. You feel that somebody is really on a mission with their heart and has that kind of gifted eye, relentless energy, and determination in the way that he practices his art. I feel very lucky to have worked with him.
The themes in this film - redemption, guilt, revenge, etc - have been tackled many times before. Was that a problem for you?
There is no re-inventing the wheel. So if we have anything original to offer, it's to speak from our own life about the society we're in. To look at the world as it is now, without recognising and acknowledging that there is a gigantic bearer of revenge and redemption, would be criminal on behalf of a filmmaker. For me, these are very central and present themes; they have to do with the lifetime that we're all experiencing. So it seemed appropriate to dramatise these things.
You're a director as well as an actor. Did you give Alejandro any advice?
I think his filmmaking speaks for itself. He takes as little advice as necessary. Like with any great director, he is open to all the creative people's input as it affects their being able to serve a function in his storytelling. But I don't think there's much of a productive crossover in terms of invading someone else's vision. What he does do is he creates an environment for the actors to aid their search, and one of the fundamental parts of that is the casting around you. I think these are actors as great as actors get in this movie.
SPOILER: In Mystic River you exacted revenge. In this you make a sacrifice in the service of peace. Is there a connection?
What happens is things come to you - director, script - and if you respond to it, it's because it's tapping into some part of what's inside you, and different roles tap into different parts. I think we all have light and dark inside us.
