2.4 Etiology and Pathogenesis: Six Evils, Seven Emotions, and Miscellaneous Causes

2.4 Etiology and Pathogenesis: Six Evils, Seven Emotions, and Miscellaneous Causes

Quick Answer: Oriental medical etiology classifies disease causation into three categories formulated by Chen Wu-ze: External causes (the Six Evils / Liu Xie), Internal causes (the Seven Emotions / Qi Qing), and Miscellaneous causes (dietary errors, overwork, sexual taxation, trauma, and parasites). The Six Evils are environmental climatic excesses that invade when Defensive Qi (Wei Qi) is compromised. The Seven Emotions perturb the physiological directional flow of Qi within specific Zang organs. Pathogenesis represents the dynamic confrontation between righteous resistance (Zheng Qi) and pathogenic invasion (Xie Qi).

Classical Classification: The Three Categories of Causes

The systematic categorization of disease causes was standardized during the Song Dynasty by Chen Wu-ze in his treatise San Yin Ji Yi Bing Zheng Fang Lun (Treatise on the Three Categories of Pathogenic Factors):

1. External Causes (Wai Yin): The Six Exogenous Pathogenic Factors (Six Evils / Liu Xie), consisting of Wind, Cold, Summer-Heat, Dampness, Dryness, and Fire. They invade from the exterior through the skin, nose, and mouth when environmental conditions are unseasonal, severe, or when the patient's Defensive Qi (Wei Qi) is depleted.
2. Internal Causes (Nei Yin): The Seven Emotions (Qi Qing): Joy, Anger, Worry (You), Pensiveness (Si), Sadness (Bei), Fear (Kong), and Shock or Fright (Jing). They cause direct interior organ injury and disrupt the directional mechanics of Qi circulation.
3. Miscellaneous Causes (Bu Nei Bu Wai Yin / Neither External Nor Internal): Lifestyle and accidental factors that do not fit neatly into climatic invasion or emotional disruption, including dietary irregularities, physical and mental exhaustion, sexual taxation, physical trauma, bites, and parasites.

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External Pathogenic Factors: The Six Evils (Liu Xie)

Under normal environmental conditions, the six climatic phases are harmless natural energies called the Six Qi (Liu Qi). They become pathogenic "Evils" (Liu Xie) when weather fluctuations are unusually rapid, extreme, or unseasonable, or when host Zheng Qi is insufficient to adapt.

Detailed Pathogenic Signatures

• Wind (Feng) — Chief of the Hundred Diseases (Bai Bing Zhi Zhang): Wind is the primary carrier pathogen; other climatic evils (Cold, Damp, Heat, Dryness) hitch a ride on Wind to penetrate the body's superficial defenses (e.g., Wind-Cold, Wind-Heat, Wind-Damp). It produces wandering urticaria and fluctuating neurological symptoms.
• Cold (Han) — The Congealing Yin Pathogen: Cold halts physiological movement, slowing down Qi and Blood flow until it coagulates. This obstruction causes severe, intense pain that is fixed in location, markedly aggravated by exposure to cold, and significantly relieved by local heat (Tong Bi / Painful Bi). Its contractive nature locks the pores and sinews.
• Summer-Heat (Shu) — The Seasonal Yang Pathogen: Excessive sweating severely depletes body fluids, leading to oliguria, dry mouth, and parched throat. Because "Qi follows fluids," severe fluid loss leads to sudden collapse of Qi: extreme physical exhaustion, shortness of breath, and syncope (sunstroke / heat exhaustion).
• Dampness (Shi) — The Heavy, Sticky Yin Pathogen: Patients report a sensation of generalized heaviness in the limbs and body, as if their head is wrapped tightly in a wet towel (Tou Zhong Ru Guo). Turbidity produces dirty, opaque, foul-smelling discharges: turbid urine, weeping eczema, greasy skin, and sticky stool.
• Dryness (Zao) — Fluid-Consuming Pathogen: Directly robs the body of lubricating moisture. The Lung requires continuous moisture to descend and diffuse Qi. Dryness attacks the Lung to cause an intractable dry hacking cough, absent or scanty tenacious sputum, chest pain, and dry skin.
• Fire and Heat (Huo / Re) — Scorching Yang Pathogens: Penetrates the Heart to cause extreme agitation, insomnia, manic raving, delirium, and loss of consciousness. It forces Blood out of the vessels (Re Po Xue Wang Xing) triggering epistaxis, hematemesis, and purulent skin lesions.

Pestilential Qi (Li Qi): The Epidemic Pathogen

The 2026 FOM outline names pestilential Qi (Li Qi) among the external etiologies, alongside wind, damp, cold, dryness, heat, and summer-heat. Wu You-ke's Wen Yi Lun (Treatise on Pestilence, 1642) argued that epidemics are caused by a distinct pathogenic Qi rather than by ordinary weather. Li Qi has four defining features:

Li Qi patterns are usually analyzed with the Four Levels or San Jiao frameworks (see Chapter 5). Biomedically, a suspected Li Qi presentation is a contagious infection. The acupuncturist's priorities are infection control, prompt medical referral, and any public-health reporting required by law (see the Biomedicine chapters).

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Internal Causes: The Seven Emotions (Qi Qing)

In Oriental medicine, emotions are normal psychophysiological responses to life experiences. They become pathogenic causes (Nei Yin) only when they are unusually intense, sudden, unexpressed, or prolonged over many months or years, directly injuring the internal Zang organs and destabilizing the directional mechanics of Qi:

Counting to seven: The table groups closely related emotions. Classical lists separate worry (You) from pensiveness (Si) and sadness (Bei) from grief. Worry knots Qi and affects both the Lung and the Spleen; pensiveness knots Qi in the Spleen. Exam items may use either the five-emotion (Five Element) list or the full seven.

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Miscellaneous Causes (Bu Nei Bu Wai Yin)

Causes that operate outside climatic invasion and emotional perturbation are grouped as Miscellaneous factors:

1. Dietary Irregularities

• Irregular Timing and Overeating: Eating too fast, eating late at night, or consuming massive portions overburdens the Stomach and Spleen, precipitating Food Stagnation (Ji Shi) characterized by foul belching, sour regurgitation, abdominal pain, and foul-smelling diarrhea.
• Excessive Raw and Cold Foods: Overconsuming iced beverages, raw vegetables, salads, and chilled fruits directly impairs Spleen Yang, extinguishing digestive fire and breeding Internal Cold-Dampness.
• Excessive Spicy, Greasy, and Alcohol: Heavy intake of deep-fried foods, red meat, pungent spices, and liquor generates internal Damp-Heat, Phlegm, and Stomach/Liver Fire.
• Contaminated Food: Causes acute toxic gastroenteritis (Huo Luan), with sudden violent vomiting and watery diarrhea.

2. Physical and Mental Overwork (Lao Juan)

• Physical Overwork (Lao Li): Prolonged heavy physical labor consumes Spleen Qi and exhausts muscular energy.
• Mental Overwork (Lao Shen): Excessive studying, intellectual concentration, and prolonged screen time consume Heart Blood and Spleen Qi, precipitating insomnia, poor memory, and digestive weakness.
• Sexual Taxation (Fang Lao): Excessive sexual intercourse and frequent ejaculations deplete Kidney Essence (Jing) and Mingmen fire, causing lower back pain, knee weakness, dizziness, and chronic fatigue.
• Excessive Inactivity (Guo Yi): Sedentary living halts Qi and Blood circulation, slows metabolic transformation, and leads to muscle flaccidity and Spleen deficiency.

3. Trauma, Bites, and Parasites

• Physical Trauma: Falls, fractures, contusions, and surgical incisions cause local Qi stagnation and Blood stasis, manifesting with localized swelling, sharp bruising pain, and potential secondary invasion by external pathogens.
• Animal, Snake, and Insect Bites: Directly introduce external toxic heat and wind-toxin into the blood, producing rapid swelling, tissue necrosis, or systemic convulsions.
• Intestinal Parasites: Derived from contaminated water or food; consume host nutrition, injuring Spleen and Stomach function and producing abdominal distension, periumbilical pain, teeth grinding during sleep (Bruxism), and voracious hunger accompanied by emaciation.