“[Documentaries] show you what was not intended for you to see. The essential documentary impulse is the impulse to catch life off camera, to film what was not planned to happen, or what would have happened whether someone was there to film it or not. That’s why people make documentaries, and why people go to see them. It’s a genre founded on a paradox.” Essay here in the New Yorker.
And while we’re on the subject, here is Geoffery O’Brian’s take on Michael Moore and his film, from the NY Review of Books.