We sort of understand how painkillers work. You take one, and it reduces your headache. We don't understand how photographs work. And that, to me, is an essential problem as a practitioner.

As humans, we need to question all these notions. What does freedom mean for us? What are our responsibilities? It takes one-250th of a second to take a photograph. So I have the whole of the rest of that second - and of that day - to think.

In the documentary impulse, two species of 'fact' exist side by side: one is coolly objective and the other is fraught, diverse and emotive one figurative, the other abstract one prosaic, the other poetic one factual, the other romantic.

The world of photography is very self-aware. Everybody is always looking around. So it's quite difficult to stand up with a megaphone and declare, This is what I think. As a reasonably shy person, I found it difficult to do that.

Well, people from the me generation use photography to show off what they are doing, to show the world themselves and their friends. Those sort of diarized accounts have always been there. But the phenomena of making those diaries public is new, isn't it?

It's quite difficult to write about photography as a photographer. A lot of better photographers than me have declined to do it.

We create these walls between fact and fiction, but often the difference between the two is as little as that between a real name and a pseudonym. So I'm not sure about those walls - certainly not in the realm of visual arts.

There's an awful lot of work being done that no one ever sees, or that is only seen in the gallery world. I feel that the public are losing touch with the great stuff that's being done in photography.

In the same way, photography, for me, has fragmented. You do have people doing bodies of work - often with found photographs - that are quite hard to understand unless you got a very sophisticated visual history behind you. But there are different camps.

Environmentalism is a personal thing - but it's also a planetary thing. It's about making deep connections. But it's also about recognizing the very human connection between species diversification and ourselves.

I think it's terribly important to reach out and understand all the different types of life and the different types of challenges that are present around the world. And I think the more people who can do that the better our planet will probably be.

Photography for me has been tremendously good, because I'm not a very sociable person. I'm happy reading or sitting in the library or going for walks. So photography has brought me in contact with people and made me understand people in a way that I probably wouldn't have done if I hadn't been a photographer. And so I'm grateful for that, really.

After my mother died, I lived with relatives. Reading was a means of escaping into other worlds, as photography, much later, was to become.

I have a huge respect for the dedication that many people have, on the other side of the Atlantic, to photography. You can count them on one hand here. There's less respect for a Magnum photographer in Britain than there is in America. It's a much more postmodern culture here.

I love photographing. I love the experience of being around all the things that surround you when you go out to do work.