The New Testament and the People of God

NT Wright is one of my favorite writers. Right now I am reading his book The New Testament and the People of God. It is really good - though it gets very technical. If you are interested in reading a book by Wright I would highly, highly recommend Simply Christian.
Back to The New Testament and the People of God. At one point Wright begins talking about the authority of the bible. To explain the authority of the bible he gives the illustration of play that has four acts written but has lost the fifth act. Now the first four acts are amazing - great plot and characterization. So the play should be done. In order to get the fifth act the actors will be invited to make it up. In order to make it up they will have immerse themselves in the first four acts. When the fifth act is then acted out it needs to be consistent with the first four acts. It has bring the play to a conclusion. Now people could argue whether the actors where right in how they acted based on the authority of the first four acts. Were they faithful to what was written? The one thing they could not do is keep re-acting the first four acts, they would have to do something new.
Wright says that this is way that the bible is authoritative. We are called to be the actors in act 5. In order to do it right we have to immerse ourselves in the first four acts (creation, fall, Israel, Jesus). Not just doing what they did, but living in a way that is faithful to what happened in the past.
Very interesting. What do you think?