This great documentary filmmaker also says that he turns on his camera in order to allow himself to be surprised. That the intuition is the most important element in his creative process. When he enters a scene first he notices things that he likes. Only afterwards he questions the blind chance of these elements to happen and asks himself "the most important questions for a filmmaker: why? What happens that these people in this specific time and place behave the way they do?" His films try to answer these questions.
Keeping sensibilities fresh (to be surprised) and maintaining the thought process clear and organized enough to be able to fish out answers to the "why" questions - that's a great formula for work.