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Qi ascending and rushing causes cough. The *Huangdi Neijing* (Yellow Emperor's Inner Canon) states: "The diseases of the five zang organs and six fu organs can all cause cough, not limited to the lung alone." However, the lung is the market where qi gathers; when various qi rebelliously ascend into the lung, it triggers choking and coughing. Therefore, cough is not solely caused by the lung, nor can it be separated from the lung.

The condition of the lung is of utmost importance, while that of the stomach is not trivial. Although the *Huangdi Neijing* distinguishes coughs caused by the five zang organs, the particular emphasis lies in the six characters: "gathering in the stomach, relating to the lung." This is because the qi of food and drink in the stomach, if unable to vaporize upwards like mist to nourish the lung and irrigate the other organs, but instead stagnates and accumulates in the stomach, will transform into phlegm with heat or into fluid retention with cold. Once the stomach is obstructed by phlegm and fluid retention, the qi transported to the lung will inevitably be impure, becoming the source of various coughs.

The lung is like a bell; it rings when struck. The lung is the canopy covering the zang and fu organs; it becomes empty upon exhalation and full upon inhalation. It can only accept its inherent righteous qi, but cannot tolerate external pathogenic qi. When external pathogenic qi interferes with it, choking and coughing occur. It can only accept clear qi from the zang and fu organs, but cannot tolerate pathological qi from them. Pathological qi interfering with it also causes choking and coughing. The lung body belongs to Metal in the Five Elements, resembling a bell; both external and internal factors are what strike it to make it ring.

Wind and cold entering cause ringing from external striking. The classics state: "Slight cold leads to slight cough." Thus, cough is often due to wind and cold. Wind enters the lung from the skin and hair, and cold enters the lung from the back shu points; both are external factors. Although later annotations mention heat, dampness, and dryness, these pathogens do not act independently but must rely on wind and cold as their leaders.

Tuberculous damage and accumulation cause ringing from internal striking. Tuberculous injury and cough are primarily internal. If these two conditions are not treated, progressing to cough and loss of voice, this is known as "broken metal does not ring" (damage to the lung tissue preventing sound production).

Who treats external cases? Liu'an Decoction is used. Although Liu'an Decoction lacks profound theoretical depth, it is stable and mild. However, for coughs caused by external pathogens, one must distinguish between wind-heat and wind-dryness syndromes. For instance, if in winter one first suffers from unseasonable warmth, followed by external constraint of wind and cold, resulting in cough, phlegm nodules, swollen throat, heavy body, spontaneous sweating, and floating pulse, this is wind-heat. It is suitable to use Weirui Tang (Polygonatum Decoction), a pungent-moistening formula, and absolutely avoid pungent-warm dispersing agents. The syndrome of wind-dryness is particularly difficult to differentiate and treat. Dryness is the qi of autumn; it does not act alone but must borrow the might of wind and cold for its command to prevail and for cough to arise. Why does the *Huangdi Neijing* only say "autumn injury by dampness"? Because during late summer, one receives the qi of damp-earth stagnation and steaming, which, following autumn's收敛 (convergence), lies latent between the lung and stomach. It waits until deep autumn when dryness commands prevail; dryness and dampness become incompatible, leading to cough in winter. This syndrome presents a dilemma of lung dryness and stomach dampness that are hard to separate. Only Maidong Tang (Ophiopogon Decoction) and Wuweizi Tang (Schisandra Decoction) from the *Qianjin Fang* (Essential Prescriptions Worth a Thousand Gold) capture the secret essence. Later generations, failing to distinguish between astringency and dispersion, discarded them for mixing drying and moistening properties, which was very ignorant.

Who treats internal cases? Follow the protocol for deficiency consumption. Select appropriate formulas from the "Deficiency Consumption Chapter." If examined to be kidney essence injury due to sexual excess, tonify essence; if examined to be spleen injury due to worry and depression, nourish the spirit.

Accompanied by water qi, Xiao Qinglong Tang calms it. Ke Yunbo treated cough regardless of season or depth; for any cold-type cough, Xiao Qinglong Tang (Minor Blue Dragon Decoction) was effective in most cases. The formula expels wind and dissipates cold, resolves the muscle layer and drives out water, benefits the lung and warms the kidney, eliminates phlegm and stabilizes wheezing, repelling the exterior and securing the interior, each function working exquisitely. Since the lung house harbors chronic cold and stubborn cold, only Mahuang (Ephedrae Herba), the general, can destroy its stronghold; how could other herbs achieve efficacy?

Accompanied by constrained fire, Xiao Chaihu Tang clears it. For cough accompanied by alternating chills and fever, it is suitable to remove Renshen (Ginseng Radix et Rhizoma), Dazao (Jujubae Fructus), and Shengjiang (Zingiberis Rhizoma Recens), and add Ganjiang (Zingiberis Rhizoma) and Wuweizi (Schisandrae Chinensis Fructus) for treatment.

Xixin (Asari Radix et Rhizoma), Ganjiang, and Wuweizi are cooked together. The treatment of phlegm-fluid and cough in the *Jingui Yaolue* (Essential Prescriptions of the Golden Cabinet) does not go beyond modifications of Xiao Qinglong Tang. Among the ingredients in the formula, most can be added or removed, but Xixin, Ganjiang, and Wuweizi are never lightly discarded. Even if the face appears hot like drunkenness, requiring Dashuang (Rhei Radix et Rhizoma) to clear stomach heat, or adding Shigypsum (Gypsum Fibrosum) and Xingren (Armeniacae Semen Amarum), these three herbs are always retained. Students of medicine must deeply ponder the reason. Xu Zhongke has discussions in his *Jingui Bianzhu*.

The methods of Changsha (referring to Zhang Zhongjing, who served as Prefect of Changsha) are detailed and refined. The treatment methods for phlegm-fluid and cough in the *Jingui Yaolue* should be studied thoroughly.