The previous comments on this book are basically accurate. The reader is correct that it does not go into detail regarding the small circualtion, but that's cause it wasn't meant to. Dr.Yang mentioned in the beginning that you should have already read and accomplished some part of the Yi Gin Ching before going on to this volume. Also he mentions that you should have READ and UNDERSTOOD what was written in hid previous books, "The Root of Chinese Chi-Gung" and "Chi-Gung, Health and the Martial Arts". The Health and the Martial Arts book is where the Small and Grand circualtion is mentioned and taught in much greater detail. I have been into REAL Gung-FU, Wu-Su for fifteen serious years now. I know that what Dr.Yang is talking about is correct cause I was taught, or heard my instructors talking about the same things as Dr.Yang for years before I read his books. I was taught by a student of a Gung-Fu Master that grew up in one of the last Shaolin Temples that was destroyed in 1927. He is now nearly one hundred years old and looks like he's about thirty, with a physique like Van Damme has in his movies, so you can be sure that he knows that Marrow washing Gung-fu as well. Dr. Yang states repeatedly in his books that you must make sure that you read and understand all the theory and comprehend it BEFORE you go on to the next level of material. Train smart and slow, NOT stupid and fast as Dr.Yang repeatedly states in his books. Just cause you may not understand something, don't assume that it's the authors fault. I'm not saying that it's all perfect, some things could be a little clearer. But being into physics myself since I was about 6 years old, and that fact that Dr.Yang also has a degree in Mechanical engineering, has greatly helped him in his ability to break down and explain the material from both a spiritual and physical point of view, from both the eastern and western view as well. Overall he has done and excellent job in his material and I peronally owe him many thanks. The knowledge has helped me to grow and learn even more and faster thah I was before, it helps me when teaching my students as well. You don't have to be into physics though to understand the material. It is difficult to undertand no matter how you look at it. Even with my experience, I took Dr.Yangs advice and read each book about thirty times, some sections more than that BEFORE I started doing anything in the books, that is what you must do to, especially if you are a newcomer to the field as well. Read "The Root of Chinese Chi-Gung" first. Read it over and over if you have to, then go on to the "Eight Pieces of Brocade" then to "Chi-Gung-Health and The Martial Arts" then, after at least two years, if you understand and have done those things seriously, I would say that you could begin some of the material in The Marrow washing volume. Follow the same pattern of reading it many times over and UNDERSTANDING the material well BEFORE you practice what is written in there. Also, FOLLOW the rules for Chi-Gung practice that are written therin and DO NOT take then lightly. I am speaking from experience here, you CAN mess yourself up and your health if you do not follow the rules that are given to you by Dr.Yang. Fortunatly I know some other healing techniques that I was able to fix what had been done to me, which was my own fault, no one elses. The techniques are safe and glorious, as long as you don't rush or take the information and warnings lightly. Do it right and you won't believe the results that you will get. Take care, all the best to you in you Chi-Gung journey.