San Yin Ji Yi Bing Zheng Fang Lun (三因极一病证方论): The Three Causes Formulary — Revolutionizing TCM Etiology

The Three Causes: A Breakthrough in Disease Classification

San Yin Ji Yi Bing Zheng Fang Lun (三因极一病证方论, Sān Yīn Jí Yī Bìng Zhèng Fāng Lùn), commonly known as the Three Causes Formulary, was compiled by Chen Yan (陈言), also known as Chen Wuze (陈无择), and completed around 1174 during the Southern Song dynasty. This work revolutionized TCM by establishing a systematic framework for understanding why people get sick — a framework that remains one of the pillars of TCM theory.

Before Chen Wuze, discussions of disease causes were scattered across various texts without a unifying system. The Huangdi Neijing mentioned various pathogenic factors, and Zhang Zhongjing’s Shanghan Lun focused on cold damage. Chen Wuze synthesized all existing knowledge into a clear, three-part classification: external causes, internal causes, and causes that are neither external nor internal (不内外因).

The Three Causes Framework

External Causes (外因): The Six Excesses

External causes are environmental pathogenic factors that invade the body from outside. Chen Wuze formalized the concept of the Six Excesses (六淫):

Pathogen	Chinese	Nature	Typical Manifestations
Wind	风	Yang pathogen, light and moving	Headache, wandering pain, stiffness, aversion to wind
Cold	寒	Yin pathogen, contracting and slowing	Severe pain, chills, contraction, pale complexion
Summer Heat	暑	Yang pathogen, hot and consuming	High fever, sweating, thirst, sudden collapse
Dampness	湿	Yin pathogen, heavy and lingering	Heaviness, swelling, sluggishness, sticky discharge
Dryness	燥	Yang pathigen, drying and withering	Dry skin, dry cough, cracked lips, constipation
Fire/Heat	火	Yang pathogen, flaming upward	Redness, fever, bleeding, mental agitation

These six environmental factors are present in nature during their respective seasons. They cause disease only when they are excessive, out of season, or when the body’s defensive Qi is weakened.

Internal Causes (内因): The Seven Emotions

Chen Wuze identified emotional excess as a major internal disease cause, systematizing the Seven Emotions (七情):

• Joy (喜) — excessive joy injures the Heart, causing Qi to scatter
• Anger (怒) — excessive anger injures the Liver, causing Qi to rise
• Anxiety (忧) — excessive worry injures the Lungs, causing Qi to congeal
• Thought (思) — excessive thinking injures the Spleen, causing Qi to stagnate
• Sorrow (悲) — excessive grief injures the Lungs, causing Qi to dissipate
• Fear (恐) — excessive fear injures the Kidneys, causing Qi to descend
• Fright (惊) — sudden fright causes Qi to become chaotic

The key insight is that emotions are not inherently harmful — it is their excess or prolongation that disrupts the organ systems and creates disease.

Neither Internal Nor External Causes (不内外因)

This third category captures causes that originate neither from the environment nor from the emotions:

• Dietary irregularities — overeating, undereating, consuming spoiled food, excessive raw or cold food
• Overwork and excessive labor — physical exhaustion that depletes Qi and blood
• Excessive sexual activity — depletes Kidney Jing (essence)
• Trauma and injuries — falls, cuts, burns, animal bites, insect stings
• Parasites and toxins — intestinal worms, poisonous substances

By creating this third category, Chen Wuze ensured that no cause of disease was left unclassified.

Historical Context

Chen Wuze practiced medicine during the Southern Song dynasty (1127–1279), a period of significant medical advancement. The Song dynasty saw the establishment of imperial medical schools, the printing and distribution of classical medical texts, and the emergence of specialized medical disciplines.

Chen Wuze was a practicing physician in Wenzhou, Zhejiang province. Drawing on the Huangdi Neijing, the Nan Jing, and the works of Zhang Zhongjing, he observed that physicians often failed to identify the correct cause of disease before selecting a treatment. His response was to create a comprehensive system where every possible cause was classified, enabling physicians to trace symptoms back to their root cause with greater precision.

Structure of the Text

The Three Causes Formulary is organized into 18 chapters (卷) containing discussions of over 1,000 conditions with corresponding formula prescriptions:

Chapters 1–2: Theoretical Foundation

These introductory chapters lay out the three causes framework in detail, explaining how each cause manifests in the body and how to distinguish between them in clinical practice.

Chapters 3–6: External Cause Diseases

Detailed discussion of diseases caused by the Six Excesses, including:

• Wind-stroke and wind-cold patterns
• Cold damage diseases
• Summer heat disorders
• Dampness-related conditions
• Dryness diseases
• Fire and heat patterns

Chapters 7–9: Internal Cause Diseases

Coverage of emotional and organ-based diseases:

• Heart disorders from excessive joy
• Liver disorders from anger
• Spleen disorders from worry and overthinking
• Lung disorders from grief and anxiety
• Kidney disorders from fear

Chapters 10–14: Miscellaneous Diseases

Diseases from the third category and complex conditions involving multiple causes:

• Digestive disorders from dietary irregularity
• Trauma and injury management
• Toxic exposures
• Parasitic diseases

Chapters 15–18: Formulas and Prescriptions

A comprehensive formulary matching each disease pattern to appropriate herbal prescriptions, including modifications for variations in presentation.

Key Contributions

1. Unified Etiological System

Before the Three Causes Formulary, disease causation was discussed piecemeal in various texts. Chen Wuze created a single, comprehensive framework that could encompass every known cause of disease. This system remains the standard etiological model in TCM education worldwide.

2. Emphasis on Emotional Medicine

By elevating the Seven Emotions to a co-equal status with external pathogens, Chen Wuze legitimized the treatment of emotional and psychological conditions within Chinese medicine — centuries before Western medicine recognized the psychosomatic dimension of illness.

3. Pattern-Based Prescriptions

Each formula in the text is tied to a specific disease pattern with a clearly identified cause. This cause-pattern-formula chain gave physicians a logical treatment pathway: identify the cause → determine the pattern → select the formula.

4. Integration of Earlier Traditions

Chen Wuze did not simply invent a new system — he synthesized insights from the Neijing, Nan Jing, Shanghan Lun, and Jin Gui Yao Lue into a coherent whole, preserving earlier wisdom while adding organizational clarity.

Influence on Later Medicine

The Three Causes framework became so fundamental that it was adopted by virtually every subsequent TCM text:

• Pi Wei Lun (脾胃论) by Li Dongyuan used the framework to argue that dietary irregularities (third category) were the primary cause of Spleen disorders
• Dan Xi Xin Fa (丹溪心法) by Zhu Danxi drew on the emotional causes category in developing his theories on stagnation
• Modern TCM textbooks worldwide still teach the Three Causes as the foundational etiological model

The Three Causes in Modern Practice

Contemporary TCM practitioners use the three causes framework every day:

1. Case taking — questions are organized around external exposures, emotional history, and lifestyle factors
2. Diagnosis — the Eight Principles and pattern differentiation build upon the Three Causes foundation
3. Treatment planning — understanding the cause determines whether to expel pathogens, regulate emotions, or correct lifestyle factors

The simplicity and comprehensiveness of Chen Wuze’s system explains its remarkable longevity — over 850 years after it was written, it remains the starting point for understanding why disease occurs.

Related Reading

• Huangdi Neijing (黄帝内经): Yellow Emperor’s Inner Classic
• Shanghan Lun (伤寒论): Treatise on Cold Damage
• The Eight Principles of TCM Diagnosis
• TCM Emotional Health