From The Village Voice:
May 6, 1965
Andy Warhol makes movies with the same unruffled objectivity that he looks at life. His usual procedure is to set up the action—often a group of people interacting—point the camera at them, turn it on, and step back. The camera makes the movie: whatever happens, planned or not, is the film. Sometimes in the studio (which he refers to as “the factory”) there will be interruptions: telephone calls, people going up or down in the elevator, somebody dropping something or walking inadvertently in front of the camera. All is recorded. No trace of surprise or annoyance registers on Warhol’s face. He is totally cool or very uptight, depending on your point of view. The latter school says: “Andy’s been trained in Madison Avenue. He’s like a high-powered executive who doesn’t show his feelings, but he’s seething inside.” Personally, I think it the height of coolness to regard everything with a detached eye and rely on intuition to make instant decisions. Warhol’s intuition is usually correct.
More here.