System concept is the core (essence) of TCM. Base on system concept, we will much easier to learn TCM text book and successful clinical cases of 5000 years experience. It is the key to improve treatment effecting rate. When we study Two-dimensional world, we use coordinates with axes of X and Y. The relationship between these 2 coordinates is: X is perpendicular with Y. The same human system can be analyzed in some axes coordinates system. But human system is much more complicated, thus our ancestors found 2D, 3D, even 4D axes system are not enough to handle human system, they invented a special axes systems: axes of 5 elements (Wood, Fire, Earth, Metal, and Water) more... See more text