The book divides humans into 12 categories. Each category corresponds to an animal. Then we are all divided into five more categories. These are wood, fire, earth, metal, and water. So all of humanity is divided into sixty categories. In a fashion to understand others and situations. Not to judge, moralize, or condemn. The book is large. Over 500 pages. This is mainly because of the range. By this, I mean that one can use this text for fun or for very serious matters. The range of this book is what I think seperates it from other Chinese astrology books that I have seen. Some are "cute." Some take themselves deadly serious. This book is versatile. It's also a bit hard-hitting. The author doesn't believe in pulling punches in regards to her descriptions of personality types