Yin and Yang 陰陽

Two sides of one whole

Chinese thought describes everything as a balance of two opposite but connected qualities. Yin is the quieter side: cool, still, dark, inward and downward, the substance of a thing. Yang is the active side: warm, moving, bright, outward and upward, what a thing does.

Neither exists without the other. Day turns into night and back again; each side holds the seed of the other, and health in traditional theory is the two kept in balance.

In the body

The front of the body is Yin and the back is Yang; the inside is Yin and the surface is Yang; the lower body is Yin and the upper body Yang.

The organs come in Yin and Yang pairs. The six Yin organs store and hold: the Lung, Spleen, Heart, Kidney, Pericardium and Liver. The six Yang organs receive, transform and pass things on: the Large Intestine, Stomach, Small Intestine, Bladder, Triple Energizer and Gallbladder.

In the channels

Every main channel belongs to one organ and is Yin or Yang with it. On each arm and each leg there are three Yin and three Yang channels. On the limbs the Yin channels run mostly along the inner side and the Yang channels along the outer side.

The six channel names describe how much Yin or Yang a channel holds: Taiyin (Greater Yin), Shaoyin (Lesser Yin) and Jueyin (Terminal Yin); Taiyang (Greater Yang), Yangming (Yang Brightness) and Shaoyang (Lesser Yang). The full name of a channel adds the limb and the organ: Hand Taiyin Lung Channel.

Yin and Yang channels pair up across the same limb: Taiyin with Yangming (Lung with Large Intestine, Spleen with Stomach), Shaoyin with Taiyang (Heart with Small Intestine, Kidney with Bladder), Jueyin with Shaoyang (Pericardium with Triple Energizer, Liver with Gallbladder).

Which way they flow

The direction of flow follows a simple rule. The Yin channels of the arm run from the chest to the hand; the Yang channels of the arm from the hand to the head; the Yang channels of the leg from the head to the foot; and the Yin channels of the leg from the foot up to the abdomen and chest. That is why a channel's points are numbered the way they are.