The zang-xiang (visceral manifestation) theory first appeared in the Huangdi Neijing (Yellow Emperor’s Inner Canon). Zhang Jingyue annotated in Lei Jing (The Classified Classic): “Xiang refers to form and manifestation. The zang (viscera) are hidden within; their form is manifested externally — hence the term zang-xiang.” In other words, zang refers to the viscera concealed within the body, while xiang refers to the observable signs reflected on the body’s exterior.

The human body possesses five zang organs (heart, liver, spleen, lung, and kidney) and six fu organs (gallbladder, stomach, small intestine, large intestine, urinary bladder, and triple burner). The zang-xiang theory regards the human body as an integrated whole with the heart as its sovereign. Each zang-fu organ operates under the governance of the heart, functioning like a small society, interconnected and working in concert.

Among them, “The heart is the monarch organ, from which the bright spirit emanates.” The heart, as the monarch, occupies the highest position, governing all the zang-fu organs and presiding over spiritual and mental activity.

“The lung is the prime minister organ, from which regulation and governance emanate.” The lung, as the prime minister, flanks the monarch, assisting the heart in governing and regulating the functions of the zang-fu organs, qi, blood, and body fluids.

“The liver is the general organ, from which strategic planning emanates.” The liver, as the general, reflects the connection between the liver and mental activity, drawing on the metaphor of a general’s deep strategic thinking. The liver is also known as the “resolute organ”: when liver qi is excessive, one becomes irritable and prone to anger; when liver qi is deficient, one is easily startled.

“The spleen and stomach are the granary organ, from which the five flavours emanate.” The spleen, as the keeper of the granary, works in concert with the stomach: the stomach governs receiving and holding, while the spleen governs transportation and transformation. After the spleen and stomach digest food, they generate qi and blood to nourish the entire body, the limbs, and all the skeletal structures.

“The kidney is the organ of strenuous work, from which skill and dexterity emanate.” The kidney is understood by some physicians as the “official in charge of construction”, in association with its functions of governing the bones and presiding over growth and development. When kidney qi is vigorous, the tendons and bones are strong; when kidney qi is deficient, one commonly suffers from lower back soreness and weakened bones.