Some of the entries are perhaps less interesting to writers than they would be to puzzle compilers or mathematicians. Having said that I think this book points the way to the future: Good writing often follows from observing some restriction. Over the centuries, 'natural' restricions have been removed or reduced. We can go back, but with restrictions of our choice not those inherited by convention. These restricions often produce completely new ways of writing. Removal may suggest a completely new way forward as well (a diferent form of de-restriction than we had ever thought of).