Book excerpt: A model for understanding the way the human spine gradually passes through five progressive stages of decline is outlined in this groundbreaking new book. It describes how each stage manifests itself, starting off with commonplace reversible conditions and progressing to the more difficult ones. At each stage, this book sets out a logical course of treatment programs and exercises, which are clearly explained so that sufferers can know when they need to stretch, take medication, or rest in bed. Now back sufferers will understand what has gone wrong with their spines and take steps to make their backs healthy and pain-free.