I have never been one of those who cares about happiness. Happiness is a strange notion. I am just not made for it. It has never been a goal of mine; I do not think in those terms.

I'm a very circumspect and prudent person, and I eliminate danger as far as it can be done.

I'm trying to find these rare moments where you feel completely illuminated. Facts never illuminate you. The phone directory of Manhattan doesn't illuminate you, although it has factually correct entries, millions of them. But these rare moments of illumination that you find when you read a great poem, you instantly know. You instantly feel this spark of illumination. You are almost stepping outside of yourself and you see something sublime.

You have to be very prudent with what you are doing and what sort of tools you are utilizing. Drones have become a wonderful new tool in filmmaking.

I couldn't roam wildly and speak secretly with villagers [in North Korea]. No way you could do that. And honestly, I didn't even try. I was realistic of what I could do and yet persuaded them into accepting numerous things that I shouldn't have filmed.

The paintings are not just on flat walls - you have these enormous niches, bulges and protrusions, as well as stalactites and stalagmites. The effect of the three-dimensionality is phenomenal. It's a real drama which the artists of the time understood, and they used it for the drama of their paintings.

For me, the distinction between documentaries and feature films is not so clear - my "documentaries" were largely scripted, rehearsed, and repeated, and have a lot of fantasy and concoction in them.