'Emergent systems have a logic all of their own: a few simple rules create something more complex than we could have designed. For a long time I thought "don't take too many" was one of the rules. After all, using the Railway Table as a model, if we all took too many books then there would be none left. But this is a tiny system sitting within the much bigger World Publishing And Books System. It is not closed off - new books can enter, other books can leave.'