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.

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 was as big a reaction after the revelations about Assad's chemical weapons. Nevertheless, that photograph did strike a singular chord. Which leads us to a larger fact: we don't understand why certain photographs create such an upheaval in one's soul. You look at them and go, "Oh my gosh." And that doesn't happen with television. It's unique to photography. Photographs are unique in that they are a frame abstracted out of reality, out of, in this case, a civil war. A single event can carry so much weight. And that is extraordinary.

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.

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.

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.

It's certainly important to include text beside documentary photographs. Furthermore, it's important to include text in a way that's useful and accessible.