What is the philosophical principle underlying Sino-Vietnamese medicine?

According to ancient Chinese philosophy (which includes medicine), two primary principles - the male or yang and the female or yin - influence man and nature. The interaction of these two principles generates the five cosmic elements - metal, wood, water, fire, and earth - that from the common substance of all living beings and also lifeless matter. Ancient Chinese philosophy held that the cosmos exercises its influence on the various parts and organs of the human body; thus, human structures have their cosmic correspondents, and human anatomy and physiology are related to cosmogony. According to this thinking, the entire cosmos influences a person's organs.

Sino-Vietnamese medicine denies the existence of disease as a primary category, whereas Western medicine sees disease as having its own existence and attacking the body from outside. Traditional Chinese and Vietnamese medicine sees disease as an imbalance between yang and yin in particular organs. The imbalance directly affects the circulation of the body's vital energy (ki). The physician discovers the nature of the imbalance and uses his knowledge of medicinal plants and traditional practices to restore the balance, to strengthen the ki, and normalise its circulation in the affected organs to re-create harmony with the universe, thus healing the patient.