This book is a perfect introduction to the zangfu, their spheres of influence and their responsibilities as set out in the first part of The Yellow Emperor's Inner Classic, the Neijing Suwen chapter 8.
The Secret Treatise starts with an overview of the first seven chapters of the Neijing Suwen, and then continues with a line by line discussion of chapter 8.
Suwen chapter 8 is a text of simplicity, clarity, and deceptive brevity which hides a wealth of powerful images and concepts. It draws an analogy between a Confucian-style court hierarchy in which the heart is emperor, the lung is prime minister and so on, and the human body. Each official or zangfu has own his range of activities, functions and interactions.
An appendix gives the Chinese text and a translation. There is also an index of all main concept and Chinese characters.