Interesting interview with Robert Wilson in Backstage, on the occasion of the recent documentary about him.
Here's a bit that will rile up some playwrights out there:
Acting is about doing something, not about reading. The easiest things are the most difficult to do on stage: to stand, to walk. Trying to stand or walk casually, naturalistically, is already to fail. There is nothing natural about being on a stage, trying to act like there is no audience in front of you. I always tell my actors that the space in the back is as important as the space in front of them. They need both to create the tension that will hold the audience's attention. It is important to get the movements right before even thinking about the text. I rehearse silently at first, without text or music. I put the movements together with the sound much later.
Talk amongst yourselves.