This book explains the principles of Traditional Chinese Medicine (TCM) and interprets them from a biomedical perspective. TCM concepts have puzzled scientists because they involve abstract entities like qi, jing and ‘meridians’ that are ambiguous and ill-defined. The functions of the vital organs in TCM theory are at odds with those of modern physiology. For example, the ‘spleen’ in TCM governs digestion, and the ‘kidney’ controls growth, sex and the warming of the body. Equally hard for the modern scientist to accept are methods of therapy based on the yin-yang principle, the model of the five elements, and the classification of illnesses not by etiology but according to constellations of symptoms (TCM ‘syndromes’). The validity of these methods and their usefulness for therapy have yet to be satisfactorily proven by the methods of modern evidence-based medicine. TCM has an important contribution to make to health care, both as complementary medicine and also as an alternative system of therapy for many illnesses. As such it is important to explain the concepts and principles of TCM for better understanding and acceptance by scientists and the informed public. This is achieved by: (a) Treating TCM entities like qi and meridians as abstractions and constructs that relate to observable physiological functions, much as the notion of ‘utility’ in economic science is used to build models for explaining and predicting consumer behavior