There are many films I would happily spend two hours with, not so many I would spend two years with. I need to be obsessed about films, because the way I work, that means two years without sleeping at all, and losing part of your life. I need to put all of my energy and heart and soul and bones and blood and skin and muscles in the things that I do.

Even when you expose something, when you have a true believer, that person rejects that proof; he thinks it's just a set-up. We believe what's more convenient for us to believe. We always behave this way. We start with the conclusion, and then we create a body of theories around it. We choose what allows us not to change.

I think being self-taught is the only way of really learning things, because you have to question everybody. You don't simply absorb axioms or so-called truths like they are rules. You have to test them, and you need to reflect on them, to consider the effect they create. So, you have very significant opinions about things, because they come out from your own reflections.

Once I do something, I need to be obsessed - or maybe I don't need to be obsessed, but I get obsessed because that's just the way my brain works - but I need to pay a lot of attention to detail. Because everything counts to me once I do something, even if it's a movie that nobody cares about. That's why I need to choose very well what I want to do. But in real life, when I watch TV or whatever, I guess I'm not that obsessive guy, and I'm pretty boring.

Debunking certain things is important, first because you question things, which is always healthy, and second because there's a part that has to do with show biz, which is pretty harmless, but there's another part that has to do with people's vulnerability. That needs to be exposed.

And as a director, you constantly try to solve problems, so you have to focus on that. You take away all the other parts. Of course, when the shot finishes, you remember that you have Robert De Niro in front of you. But when you're shooting, you just see a character in front of you, and an actor, and you try to search for very truthful moments. That's what obsesses you.

If you believe in God, that's a belief. If you are an atheist, it's a belief too, because you cannot prove that God does not exist.