What nourishes the human body is solely Qi and Blood. Regular respiration, with a steady interval between breaths, is the normal state of Wei Qi (Defensive Qi); when this state is disrupted, it leads to cough; the flowing and moistening of body fluids is the normal state of Ying Blood (Nutritive Blood); when disrupted, it produces phlegm and saliva. Coughing accompanied by expectoration indicates that Qi and Blood have already become disordered.

Although there are numerous medicines in the world for treating cough, they ultimately cannot be universally effective, largely because the causes of disease vary. The so-called "Five Coughs" discussed by people are described from the perspective of the Five Zang Organs. However, essentially, internal factors such as the Seven Emotions (Joy, Anger, Worry, Pensiveness, Sorrow, Fear, Fright), external factors such as the Six Excesses (Wind, Cold, Summer-heat, Dampness, Dryness, Fire), improper diet and daily life, excessive sexual activity, or loud shouting, can all cause disease either singly or in combination. Therefore, the *Classic* states: "The Five Zang and Six Fu organs, upon contracting cold, heat, wind, or dampness, all cause cough." Additionally, slight cold induces slight cough; being blown by fierce wind causes hoarseness and cough; heat in the Upper Jiao (Upper Burner) leads to Lung Wei (Lung Atrophy/Withering); injury by dampness in autumn and cough in winter are all external causes. Joy scatters Qi, anger agitates Qi, worry gathers Qi, pensiveness knots Qi, sorrow tightens Qi, fear sinks Qi, and fright disorders Qi; all these can induce cough, constituting internal causes. As for cough caused by consuming raw/cold foods or overexertion due to sexual activity or labor, these are particularly common and belong to neither internal nor external causes, termed "neither internal nor external causes." Can one single method treat them? Treatment must deduce the Three Causes, and based on pulse and syndrome differentiation, employ methods such as dispersing, purging, warming, or inducing vomiting, aiming to restore balance.

Cough due to Wind Injury presents with aversion to cold and high fever, spontaneous sweating, aversion to wind, dry mouth, and irritability; Cough due to Cold Injury presents with aversion to cold and fever, absence of sweating, aversion to cold, irritability, but no thirst; Cough due to Summer-heat Injury presents with vexatious heat and desire for drinking, dry mouth, possibly vomiting saliva, hoarseness, or hemoptysis; Cough due to Dampness Injury presents with painful joints, heavy limbs, and a sensation of chilliness (shivering). These all belong to external causes. Upon examining the pulse, floating indicates Wind, tight indicates Cold, rapid indicates Heat, and fine indicates Dampness. Corresponding to the Renying acupoint (Renying, ST9, used to assess Yang meridians) based on the location of the pathology; and by deducing the involved Zang-Fu organs, the source of the disease can be identified.

Excessive Joy damages the Heart, causing cough with a sensation of swelling in the throat, and severely, sore throat and throat obstruction; this is named Heart Cough. If unresolved, it transmits to the Small Intestine; Small Intestine Cough presents with cough accompanied by flatus. Excessive Anger damages the Liver, causing cough with pain under both hypochondria, and severely, inability to turn the body, turning causes fullness under both hypochondria; this is named Liver Cough. If unresolved, it transmits to the Gallbladder; Gallbladder Cough presents with cough and vomiting of bile. Excessive Pensiveness damages the Spleen, causing cough with pain under the right hypochondrium, radiating faintly to the shoulder and back, and severely, inability to move; this is named Spleen Cough. If unresolved, it transmits to the Stomach; Stomach Cough presents with cough and vomiting, where roundworms may be expelled. Excessive Worry damages the Lungs, causing cough with wheezing and audible breathing sounds, and severely, spitting blood; this is named Lung Cough. If unresolved, it transmits to the Large Intestine; Large Intestine Cough presents with cough accompanied by loss of stool and urine. Excessive Fear damages the Kidneys, causing cough with pulling pain between the waist and back, and severely, coughing up saliva; this is named Kidney Cough. If unresolved, it transmits to the Bladder; Bladder Cough presents with cough accompanied by urinary incontinence. Chronic cough that does not resolve transmits to the Sanjiao (Triple Burner). Sanjiao Cough presents with cough, abdominal fullness, and lack of appetite. All these conditions gather in the Stomach and relate to the Lungs. Since the Shu points of the Lungs (Back-Shu points of the Lung) are closest, internal causes often involve prior sensory/emotional impact, which people generally name as Lung Cough; these all belong to internal causes. Upon examining the pulse, corresponding to the Qikou acupoint (Radial artery at the wrist, used to assess Yin meridians and Zang organs) based on location, floating and tight indicates deficiency-cold, deep and rapid indicates excess-heat, wiry and choppy indicates blood deficiency, and surging and slippery indicates excess phlegm. By analogy, no treatment is impossible.