Here's another Peter Brook quotation, this one from Between Two Silences.

I think that the only thing that really concerns us in working is to try to know what the heart of the theatre experience is, an to work outwards from it. It's a very strong question: why? Why make theatre? Why impose something of one's own on other people? Or, why waste one's time going to watch other people's efforts? That is the question that's at the heart of the experience. If one doesn't start from that question, then one goes often into endless theoretical discussions about commitment. Am I sufficiently committed? Should the other person be more committed? Should the audience be responding better? These are not primary questions; they're secondary questions. If one's clear about why it's essential to make a certain experience, if one's really convinced of this, then other people can also be convinced. Now, how can one be convinced about the "why" of making theatre? There is no point whatsoever in going into a theatre space to experience something that you can get outside it. Simple common sense.