Kathy Sierra writes about enchanting users. She's talking about user interfaces on software, but the idea stretches further.

The best user experiences are enchanting. They help the user enter an alternate reality, whether it's the world of making music, writing, sharing photos, coding, or managing a project. Even a spreadsheet has the potential to be as engaging as a game.

Until the interface comes crashing into your virtual world, throwing you back to the real one. That intense feeling of being engaged--the flow state--is interrupted. The spell is broken.

I feel the same way about facilitation. It's all to easy for the facilitator, or the facilitator's technique, to get in the way of participation. There's a certain wisdom in knowing when to use very minimal intervention in discussions.