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For males, use the left hand; for females, the right hand. The distance between the two transverse creases on the inner side of the second phalanx (middle joint) of the middle finger constitutes one Cun (同身寸). Measure using the pith of a rice straw. If thin bamboo is used, it may easily break. If waxed paper is used, it sticks to the hand and is inconvenient. If a string is used, its elasticity leads to inaccuracy. Using rice straw pith is readily available and accurate.

The Lung weighs three jin and three liang. It has six lobes and two ear-like appendages, totaling eight lobes. They hang downwards like a canopy, attached to the third thoracic vertebra of the spine. In the center, there are twenty-four hollow spaces arranged in rows. (One square Cun equals one Liang. According to current standards of weight and measure, originating from the Huangzhong pitch pipe, one ancient Liang is equivalent to slightly more than four Qian in modern terms.)

The West corresponds to the color white. Its Qi internally connects with the Lung. It opens into the nose. Essence is stored in the Lung. Therefore, diseases manifest in the back. Its flavor is Pungent (Xin). Its elemental category is Metal. Its associated domestic animal is the Horse. Its associated grain is Shu (Millet).

The West generates Dryness. Dryness generates Metal. Metal generates Pungency. Pungency generates Lung Qi. Lung Qi nourishes the Skin and Hair. The Qi of Skin and Hair returns to the Kidney. The Lung governs the Nose. In Heaven, it is Dryness. On Earth... its flavor is Pungent. In emotions, it is Sorrow. Sorrow damages the Lung. Joy overcomes Sorrow. Heat pathogenic factors damage the Skin and Hair. Cold overcomes Heat. Pungency damages the Skin and Hair. Bitterness overcomes Pungency. As recorded in *Su Wen* (Basic Questions): The Danzhong (Constrictor Vessel/Pericardium region) is the official of the minister and envoy, from which Joy and Happiness emerge.

The Lung is the root of Qi and the residence of Po (Corporeal Soul). Its luster manifests in the hair, and its substance fills the skin. It belongs to Yang within Yin (Taiyin), and communicates with the Qi of Autumn. As recorded in *Su Wen*: The Lung combines with the Skin and Hair, and its luster is in the hair. The Lung is controlled by the Heart. Lung Qi connects to the nose. When the nose functions harmoniously, one can distinguish odors. As recorded in *Nan Jing* (Classic of Difficult Issues): When Lung Qi is deficient, one dreams of white objects or sees people being slaughtered with bloodstains. If this occurs during the three months of Autumn, the condition worsens.

The color of the Lung should be white, resembling goose feathers [lustrous], not salt [dull]. As recorded in *Su Wen*: The white color of the Lung resembles Metal. Metal sinks when it meets water; why does the Lung float when it meets water? Because the Lung is not pure Metal, but rather Xin-Shang (a term referring to the soft aspect of Metal/Golden element), the soft expression of Bing Fire. ...When it sinks again, Xin should return to Geng (the hard aspect of Metal). Things turn into their opposites when they reach the extreme. When Lung Qi perishes, the Skin and Hair become scorched and dry. Lung Qi circulates through the Skin and Hair; if Qi fails to nourish, the Skin and Hair become scorched and dry. Scorched and dry Skin and Hair lead to the loss of Body Fluids. Loss of Body Fluids injures the joints of the skin. Injury to the skin joints causes the skin to wither and hair to break. When hair breaks, it indicates that the hair dies first. The condition deteriorates on Bing days and death occurs on Ding days. As recorded in *Nan Jing*.