'Butch Cassidy' was the only film I ever enjoyed making.

I don't know what your childhood was like, but we didn't have much money. We'd go to a movie on a Saturday night, then on Wednesday night my parents would walk us over to the library. It was such a big deal, to go in and get my own book.

Problems can become opportunities when the right people come together.

Essentially, my kids grew up with the emphasis on the environment because I became a political activist in about 1969 and it was not an easy time. Those were the days when the oil and gas companies pretty much controlled the show and anybody speaking about solar energy or carbon energy would get smashed down as being a radical or a tree-hugger or what have you. So I was out there feeling very often alone and my kids would get that.

I was raised in California during the Second World War and into the '50s and everything was fine, everything was great. The sun always shone, everybody looked healthy and wore ties and smoked in restaurants, and there were cars for everybody - except us, because I came from a lower class neighbourhood. But [in France] I realised there was a different point of view, so when I came back to America a year and a half later I was much more focused on my own country culturally and politically.

The technology available for film-making now is incredible, but I am a big believer that it's all in the story.

I am a cynical optimist. Big opening weekends are like cotton candy. The films you will remember over time are the films that stick in the consciousness of the audience in a good way.