https://www.youtube.com/watch?v=npW9wwB1bDc

(Introduction) The Starting Point of Basic Concepts in Sasang Medicine

Today, while previously discussing sarcomatoid carcinomatosis, we touched upon the constitution of animals. For those who are new to Sasang medicine or unfamiliar with Eastern philosophy, I would like to introduce some of its fundamental concepts.

In Eastern thought—rooted in Chinese culture—when describing a form, it is not referred to simply as “shape.” Instead, the term combines both form and essence, expressed as “form-body” (形態, 형태).

“형 (form)” corresponds to shape, while “태 (essence or disposition)* adds the dimension of inherent character or nature.

Thus, “형태 (form-body)” encompasses both shape and character.

1) The Nature of Matter and Yin–Yang
The matter we are familiar with can broadly be divided into three states: solid, liquid, and gas. However, these three states do not represent fixed essences; rather, they are merely moments within a continuous process of transformation.
There are two fundamental forces that constitute matter. One is vibrational energy, and the other is gravitational force (universal gravitation).

In Eastern thought, this is described as “Yang governs transformation (陽主神), and Yin forms structure (陰成形).”
In other words, within Eastern philosophy, Yang corresponds to vibrational energy, while Yin corresponds to a force akin to universal gravitation, which gives rise to form and structure.

2) Form, Character, and Concept
Matter, formed through the two forces of Yin and Yang, possesses form.
Form, character, and concept—within Eastern morphology, form is not regarded as a single, simple concept. Rather, it is understood as comprising two aspects. One is “form” (形), which refers to the visible, physical appearance. The other is “state” (態), which encompasses the inherent qualities, condition, and the internal image contained within.

When we observe an object, we tend to think that we are merely seeing its boundaries or external shape. However, this is not truly the case.
What we call form already contains within it an inherent nature. The physical appearance itself reveals the internal state and character. Therefore, form is not merely a shell; it is the outward expression of the forces and qualities operating within.
The visible shape is a trace of invisible activity—it is the manifestation of an internal order expressed externally. Form is not something fixed. It does not exist as a static shell, but is continuously generated as the result of directional forces.
If we observe a cube and a sphere within an image, we can recognize that forces with specific directions are acting internally. The form changes depending on the direction and balance of these forces. A linear, strongly directional force produces angular structures, whereas a force that radiates evenly from the center produces rounded structures.
Ultimately, form is not merely appearance, but action.
Form (形) is the visible result, while state (態) is the internal nature that gives rise to that result.
Therefore, when we observe form, we are not simply perceiving shape; we must also understand the forces and qualities operating within it.
In other words, this can be expressed as form and force.

The academic framework that explains such forms is precisely Sasang (Four Constitutions) and the Five Elements (Wu Xing).
Sasang refers to the static aspect of form, that is, shape itself.
In contrast, the Five Elements represent the internal forces hidden within that shape, namely energy.

3) The Three States of Matter
The matter we are familiar with can broadly be divided into three states: solid, liquid, and gas. However, these three states do not represent fixed essences; rather, they are merely transient phases within a continuous process of transformation.
There are two fundamental forces that constitute matter. One is vibrational energy, and the other is gravitational force (universal gravitation).
In Eastern thought, this is expressed as “Yang governs transformation (陽主神), and Yin forms structure (陰成形).”
In other words, within Eastern philosophy, Yang corresponds to vibrational energy, while Yin corresponds to a force akin to universal gravitation, which gives rise to form and structure.

Newton, while sitting under an apple tree, contemplated the principle behind a falling apple, and through this reflection, he arrived at the discovery of universal gravitation.

He discovered that between two bodies there exists an attractive force proportional to their masses and inversely proportional to the distance between them.
Although Eastern philosophy did not formalize this principle mathematically, it had long recognized that a converging, Yin-like force exists in nature.

Thus, this was expressed in Eastern thought as “Yin forms structure (陰成形)”, meaning that Yin energy gives rise to form.
The other fundamental aspect is vibrational energy, which possesses the inherent tendency to move continuously and to expand or disperse.

These two forces interact and counterbalance each other, giving rise to the three states of matter: solid, liquid, and gas.
A solid is a state in which internal particles are strongly bound together. Gravitational (attractive) force is dominant, causing the particles to pull toward one another. As a result, the form is firmly maintained, and the external shape remains stable and fixed.
A liquid represents an intermediate state. Here, attractive force and vibrational energy are in relative balance. Consequently, the form is not rigidly maintained; it flows and changes freely depending on the surrounding conditions.
A gas is a state in which vibrational energy is dominant. Internal particles move apart from one another and spread outward, failing to maintain a definite form and instead diffusing throughout the available space.

These three states are not separate or isolated; rather, they are in a constant process of transformation into one another. A solid, when supplied with heat and energy, becomes a liquid, and a liquid can further transform into a gas. Conversely, when energy decreases, a gas condenses into a liquid, and a liquid solidifies into a solid.
The important point is that the form of matter is not fixed. All forms are determined through the continuous interaction of two invisible forces. One is the inward-pulling force, namely attraction (gravitational force). The other is the outward-driving force, namely vibrational energy.

Within the balance and tension between these two forces, the state of matter is determined, and from that state, form is created. Therefore, the state of matter is not merely a simple classification, but the revealed result of the equilibrium among the forces acting within it. In other words, all substances do not simply exist independently; rather, their forms and properties are shaped according to the balance of the forces operating internally — namely, the balance between Yin and Yang.

Human constitutions also differ according to the distribution of these Yin and Yang forces. Interpreting these constitutional differences through the theory of Yin and Yang is what Sasang medicine, or Sasang typology, seeks to explain. Furthermore, not only human constitutions, but all matter and energy in the universe — from neurotransmitters and electrolytes to hormones within the human body — can also be categorized into four distinct constitutional categories through this framework.

The appearance and properties of matter are determined by its state. At this point, two fundamental forces are at work.
One is the inward-pulling force, namely attraction, and the other is the outward-driving force, which pushes matter outward.
First, consider the case in which the attractive force is stronger than the outward force. In this situation, matter strongly condenses inward, forming a rigid and fixed structure. This is the state of a solid. The form is maintained, and the structure becomes stiff and stable.
Next is the state in which the two forces are in balance. Attraction and the outward force oppose each other, with neither being dominant. In this case, matter does not maintain a fixed shape, yet it does not completely disperse. It flows and continuously changes—this is the state of a liquid.
Finally, consider the case in which the outward-driving force is stronger than the attractive force. Internal cohesion weakens, and matter expands outward without maintaining clear boundaries. This is the state of a gas. Form disappears, and unlimited expansion occurs.
Ultimately, matter always behaves according to the relative magnitude of these two forces. The state it takes is not determined by an intrinsic, fixed essence, but by which force is dominant at a given moment. Therefore, matter does not exist in a predetermined way; rather, it behaves precisely according to the direction of the dominant force—that is, the prevailing vector.
The concepts of energy and universal gravitation discovered in Western science correspond, in essence, to the Eastern philosophical principle described in the Huangdi Neijing as “Yang governs transformation, and Yin forms structure (陽主神 陰成形).”

Here is your passage translated into refined, lecture-style academic English:

4) The Philosophy of Form – Yin Forms Structure (陰成形)

Yin gives rise to form. The character “form” (形) is associated with the water radical, symbolizing not merely an external appearance, but a deeper connection to the properties of water and ice—namely, the capacity to condense and stabilize.

In ancient thought, water was understood as the energy of the north, which in turn represents the essential nature of Yin. Yin is cold, contracting; it gathers what is dispersed and brings movement to rest.

The Meaning of Form – Yin Forms Structure (陰成形)
Yin gives rise to form. The character “form” (形) is associated with the water radical, symbolizing not merely an external appearance, but a deep connection to the properties of water and ice—namely, their capacity to condense and stabilize.
In ancient thought, water was regarded as the energy of the north, representing the essential nature of Yin. Yin is cold and contracting; it gathers what is dispersed and brings movement to rest.
Within the material world, this action of Yin manifests as intermolecular attraction. It pulls moving particles toward one another, binding them within a single structure and preventing them from dispersing outward. Just as water, when it comes together, coheres into a unified mass, the direction of this force is inward.
As a result, form is created. Form is not merely an outward appearance; rather, it is the result of Yin force acting internally—fixing particles in place and establishing a structural framework.
As illustrated conceptually, forces acting inward from all directions compress matter and generate internal structure. The stronger this force becomes, the more distinct and rigid the form appears.
Ultimately, Yin is not merely a passive or static concept, but an active principle that generates form.
Form is the result, and Yin is the cause that produces it.

5) The Philosophy of State – Yang Governs Transformation (陽主神)
In the Huangdi Neijing, it is stated that “Yang governs the spirit” (陽主神).
Here, “spirit” (Shen) refers to that which is in motion yet has no visible form—namely, energy. Although a directional force—a vector—clearly exists, its form itself cannot be seen. Its presence can only be understood through the movement of matter.
Thus, Yang represents the dynamic, invisible force that drives change and motion, revealing itself only through its effects.

The Meaning of State (態) – Yang Governs Transformation (陽主神)
In the Huangdi Neijing, it is expressed that “Yang governs the spirit” (陽主神).
Here, “spirit” (Shen) refers to that which is in motion yet has no visible form—namely, energy. A directional force—a vector—clearly exists, yet its form itself cannot be seen. Its presence can only be understood through the movement of matter.
In Eastern thought, the fundamental image used to describe this non-material, non-Yin-like energy is fire.
Water, when it encounters itself, coheres—two droplets merge into one; it unites and condenses. Fire, however, behaves in the opposite manner: it spreads outward and disperses.
Thus, in the I Ching, the Li trigram (離卦), which represents fire, is associated with this expansive and diffusive quality.

That which disperses like fire—when we speak of separation, the term “li” (離) signifies precisely this: scattering apart like fire, moving away from one another into distance.
The character “state” (態) is composed with the element “heart–mind” (心) at its core. This heart corresponds to fire. In the context of the human body, within the framework of the Five Organs, this is also expressed as fire.
The reason the heart radical is embedded in the character 態 is that it does not merely indicate a static condition. Rather, it represents the invisible internal activity—the flow of mind, spirit, and energy.
In ancient thought, the heart is directly associated with fire, which symbolizes the essential nature of Yang. Yang is hot, expansive, and continuously moving and transforming. This activity of Yang manifests as vibration and energy—a force that constantly seeks to move outward from within, to expand beyond boundaries.
Yang does not possess a fixed form. It does not remain confined within shape; instead, it is always in motion, advancing from the inside toward the outside. In this process, it pushes against existing structures, sometimes even breaking them, thereby generating new transformations.
As conceptually illustrated, there exists a force that radiates outward in all directions from a central point. This force originates at the core and expands outward, creating tension within structures and driving change.
Ultimately, Yang is an invisible operation, a force that transcends form. Shen (spirit) is the expression of this operation. Therefore, Yang governs Shen and becomes the fundamental source of invisible mind, movement, and dynamic activity.

6) The Duality of Yin–Yang and the Structure of Existence
All phenomena in the world arise through the interaction of two fundamental forces. These two forces are Yin and Yang.
First, Yin is the inward-pulling force. It operates as attraction, gathering what is dispersed, bringing movement to rest, and forming structure. This force gives rise to form.

7) Nature (性) and Innate Energy
The concept of “nature” (性) does not simply refer to personality or temperament. Rather, it denotes the fundamental energetic structure that a being possesses from the very moment of birth.

8) The Five Elements – The Philosophy of Directionality
The Five Elements (Wu Xing) are not substances. They are often understood as wood, fire, earth, metal, and water, but this is not their true essence.
The Five Elements are not material entities; rather, they represent the directionality of forces as manifested through matter.

It also signifies circulation. While expressing force, it simultaneously completes the whole through continuous cyclical movement. By maintaining patterns of flow, it sustains the phenomena of life.
Just as a clock spring is wound and then unwound, within the inner workings of life exists the principle of the ascending and descending movements of Yin and Yang. When this flow is interrupted, death ensues.

9) Taiji and the Four Images (Sasang)
The concept of Sasang (Four Images) in Sasang medicine originates from the I Ching (Zhouyi). Its foundation begins with Taiji (the Great Ultimate), which divides into Yin and Yang, and then further unfolds into the Four Images (Sasang).

10) The Founding of Sasang Medicine
By applying the principles of the I Ching, the Neo-Confucian scholar Dongmu Lee Je-ma (1837–1900, Joseon Dynasty) established a new medical system. He integrated the conceptual framework of Neo-Confucianism with the theory of the Five Types of Humans (五態人論) described in the Tongcheon chapter of the Huangdi Neijing, thereby creating what is now known as Sasang medicine.

황제내경의 오태인논에서는 태양인 소양인 태음인 소음인의 4체질외에 음양화평인을 두어서 모두 5가지로 분류했지만 음양화평인은 수양을 통해서 음양을 발란스를 맞추는 것으로 사람의 바탕인 체질은 지축이 23.5 도 기울어져서 4계절이 나타나듯이 편파적으로 어느 한쪽방향으로만 타고 나지만 이를 수양을 통해서 극복을 하면 음양화평인 즉 성인이 된다고 보았다. 그래서 체질은 4가지가 있고 지상에 중용 즉 음과 양이 일치 하는 물질은 없다고 보는것이다. 이게 사상학의 가장 근원이다.

In the “Wutairen Theory (五態人論)” of the Huangdi Neijing, humanity was classified not only into the four constitutions — Taeyangin, Soyangin, Taeeumin, and Soeumin — but also included a fifth type known as the “Eumyang Hwapyeongin” (陰陽和平人), the person of harmonious Yin and Yang.

However, this harmonious type was not regarded as an innate constitutional type. Rather, it was understood as a state attained through self-cultivation and disciplined refinement, by bringing Yin and Yang into balance. Just as the Earth’s axis is tilted by 23.5 degrees, creating the four seasons, human beings are also born with an inherent constitutional bias toward one side or direction. In other words, each person is born with a certain constitutional inclination rather than in a perfectly balanced state.

Yet through cultivation, discipline, and spiritual refinement, one may overcome this innate imbalance and approach the state of Yin-Yang harmony — the state of the sage, or enlightened person. Therefore, Sasang typology fundamentally recognizes only four innate constitutions, because within the material world there exists no substance that is perfectly centered in absolute equilibrium between Yin and Yang.

This idea forms one of the deepest philosophical foundations of Sasang constitutional medicine.

By applying the four fundamental energies used in the I Ching to classify phenomena, he extended this framework to the human body and to all things, thereby establishing a new system of constitutional medicine.
Sasang medicine classifies individuals through a method of phenotyping, by correlating the static aspect (Sasang, as form) with the internal directional forces (the Five Elements as energy) within the human body, and applying this understanding to medical practice.

Furthermore, the foundation of Sasang medicine is not limited to the human body alone. It holds that all entities—including plants, animals, and minerals—as well as internal biological components such as electrolytes, hormones, and proteins within the human body, can also be classified according to the principles of Sasang.

11) The Structure of Sasang Types and the Seasons
Each Sasang constitutional type embodies the energy of a particular season.
The Taeyang type corresponds to spring,
the Soyang type corresponds to summer,
the Taeeum type corresponds to autumn,
and the Soeum type corresponds to winter.

In nature, during spring and summer, energy ascends. Yang energy operates by absorbing water and expanding, leading to the uptake of fluids and the initiation of life processes.
In contrast, during autumn and winter, energy descends. Water is released, dehydration occurs, and contracting Yin energy becomes dominant. This inward-converging force condenses internally while expelling moisture.
Yang-type and Yin-type individuals exhibit corresponding differences in fluid metabolism within the human body.
Yang types tend toward a hypervolemic tendency, whereas Yin types tend toward a hypovolemic tendency.
Freshwater fish are unable to effectively excrete sodium (Na). As a result, they cannot survive in saltwater. They exhibit a physiology characterized by high sodium absorption and relatively weak potassium (K) excretion. The physiology of Yang types is analogous to this, with a strong capacity for sodium absorption and a relatively weak ability to excrete potassium.
In contrast, Yin types resemble marine fish. Marine fish live in saltwater without swelling because they continuously excrete sodium while absorbing potassium. The physiology of Yin types follows a similar pattern. As a result, they tend toward increased diuresis, and as urinary excretion becomes more active, they are more prone to dehydration.
A more detailed discussion of these constitutional characteristics will be addressed later; for now, this serves as a broad overview.
At this stage, we will focus on the Five Element-based energetic properties that constitute the temperament of Sasang types.

Taeyang (greater Yang) and the Upward Energy of Wood
In terms of the Five Elements, the Taeyang type possesses an ascending, directly rising energy. For this reason, it is represented by Wood. The straight, upward directionality of Wood—symbolized by the vertical growth of a tree—captures the essence of Taeyang.
Thus, a Taeyang individual is born with a linear and direct character. This energetic pattern, as understood in the framework of yun-gi (cosmic movement and energy dynamics), shapes the physique, temperament, and even the pathological tendencies of the Taeyang type.

In this type, the function of the upper burner—particularly the Lung system—is well developed, whereas the function of the middle and lower burners—especially the Liver system—is relatively weak.
They tend to have a constitution characterized by the ability to exhale for a long duration while inhaling briefly.
In terms of sensory function, the ears are particularly well developed, making them highly sensitive to sound.

Like a deer that holds its neck upright, this type possesses strength in the neck but is born with relative weakness in the lower back. For this reason, it is described as “strong Lung and weak Liver” (肺大肝小), indicating a constitution with vigorous Lung activity.
When a bullet travels through a straight barrel, it moves forward in a direct line. This is because the dispersive forces are constrained, allowing the energy to be focused entirely in a linear direction. Such is the nature of Taeyang energy.
For this reason, it is likened to spring. It possesses strong concentration, and once initiated, it extends continuously, much like a line that keeps lengthening without interruption.

• 소양체 (少陽體): Soyang constitutional type
• 소양인 (少陽人): person of the Soyang constitution

The term “Soyangche” (少陽體) refers to the constitutional framework or structural tendency itself, whereas “Soyangin” (少陽人) refers to the actual person who possesses that constitutional nature.

In other words, “Soyangche” describes the constitutional pattern as a typological principle, while “Soyangin” indicates an individual human being in whom that Soyang constitutional tendency is embodied.

Within Sasang typology, the suffix “-che (體)” signifies the constitutional body, structural tendency, or energetic framework, whereas “-in (人)” signifies the person categorized according to that constitution. Therefore, Soyangche can be understood as the constitutional archetype, and Soyangin as the human manifestation of that archetype.

Soyang and the Expansive Energy of Fire
The Soyang type corresponds to the middle and upper regions of the body. Like the branches of a tree spreading outward, or flames flickering and dispersing in all directions, this constitution is characterized by an expansive and diffusive energy. It is represented by Fire.
Individuals of this type tend to have keen vision and high activity levels, yet they are also prone to restlessness and distractibility. The middle–upper burner, particularly the Spleen system (digestive function), is well developed, contributing to an active and dynamic physiology.
Whereas the Taeyang type is characterized by a long, upright neck like that of a deer,

The Soyang type is characterized by a well-developed chest and arms, resembling animals such as lions or tigers. They possess high visual sensitivity and tend to have a strong inclination toward external expression and artistic sensibility.
Their movements are quick and agile, and they are perceptive, with a keen awareness of their surroundings.
Whereas the Taeyang type is capable of sustained, long-term exertion, the Soyang type tends to exhibit explosive bursts of energy, but their strength is not maintained for extended periods.

In Sasang terminology, this is described as “large Spleen and small Kidney” (脾大腎小). The chest is well developed, while the hips tend to be relatively smaller.
This type is highly sensitive to the visual world and possesses strong observational ability. Rather than focusing on inner states, they are more attuned to the external, visible world—demonstrating keen perception of outward behavior and appearance.
They also exhibit a pronounced muscarinic tendency.
Taeeum type and Taeeumin …

Taeeum Type and Taeeumin
The Taeeum type corresponds primarily to the middle and lower regions of the body, and is characterized by a strong inward-converging and storing energy. In terms of the Five Elements, it is associated with Metal, representing condensation, containment, and structural solidity.
In Sasang terminology, this type is described as “large Liver and small Lung” (肝大肺小). The lower body—particularly the waist, hips, and abdomen—is well developed, while the upper body tends to be relatively less prominent.
Physiologically, the Liver system, associated with storage, metabolism, and internal regulation, is strong, whereas the Lung system, which governs dispersal and outward expression, is relatively weak. As a result, this type tends to retain and accumulate, rather than readily release.
In terms of temperament, Taeeumin are generally stable, enduring, and internally focused. They possess strong persistence and the capacity for long-term accumulation, but may be less inclined toward rapid change or outward expression.
Their sensory and cognitive tendencies are directed more toward internal processing and integration, rather than external stimulation.
From an energetic perspective, this type reflects a dominance of converging Yin force, forming a constitution that is solid, grounded, and centripetal in nature.

When the human body is divided vertically into upper and lower regions, Sasang medicine classifies them as follows: the Lung belongs to the upper burner (upper region), the Spleen to the upper–middle region, the Liver to the middle–lower region, and the Kidney to the lower region.
In this type, the middle–lower region, particularly the Liver system, is well developed, leading to a strong and well-developed waist. In contrast, the neck tends to be relatively weaker.
Thus, similar to animals such as elephants or hippopotamuses, they tend to hold their head lower while maintaining a strong and stable lower body.

They tend to inhale deeply and engage in prolonged contemplation, but have relatively weaker strength in lifting the head and in forceful exhalation. As a result, they are prone to extended deliberation and difficulty in making decisive judgments.
Compared to the visually oriented world of the Soyang type or the auditory sensitivity of the Taeyang type, they are less attuned to sight and hearing. Instead, they possess a heightened capacity for olfactory perception, enabling them to detect subtle cues and to discern human emotions with sensitivity.

They tend to exhibit relatively high levels of dopaminergic activity, making them more susceptible to emotional influence, with emotion serving as the primary driver of action.
Unlike the Taeyang type, which tends to act based on rational judgment, the Taeeum type is more inclined toward emotional decision-making, where preferences—such as feelings of liking or disliking—serve as the central criteria for evaluating situations.

The Soeum type corresponds primarily to the lower region of the body and is characterized by a deeply inward-converging and conserving energy. In terms of the Five Elements, it is associated with Water, representing storage, preservation, and latent potential.
In Sasang terminology, this type is described as “large Kidney and small Spleen” (腎大脾小). The lower body tends to be relatively well developed, while the digestive system is comparatively weaker.
Physiologically, the Kidney system, which governs storage, endurance, and fundamental vitality, is strong, whereas the Spleen system, associated with digestion and transformation, is relatively weak. As a result, this type tends toward conservation rather than expenditure.
In temperament, Soeumin are generally cautious, introspective, and selective. They prefer stability and efficiency, focusing on essential matters rather than excess. Their strength lies in refinement, precision, and the ability to preserve what is most important.
From an energetic perspective, this type reflects a deeply condensed Yin force, forming a constitution that is quiet, internalized, and highly conserving in nature.

In this type, the descending energy is well developed, leading to the prominence of the lower region (lower burner). This lower region is referred to as the Kidney system (腎局), which, in terms of body structure, corresponds to the hips and pelvis.
Whereas the Taeeum type is characterized by a relatively weaker neck and a well-developed waist, the Soeum type exhibits a weaker chest and a more developed hip region.

They resemble animals such as rats or kangaroos, with a relatively small chest and well-developed hips. They tend to keep the chest contracted, and the arms are comparatively weaker, making them less inclined toward physical exertion. They also tend to avoid heavy loads or anything that places a burden on the shoulders.
This type possesses a strong capacity for storage and concealment. Like the roots of winter, they have a tendency to preserve, hide, and maintain confidentiality, often keeping secrets to the very end.
Rather than being aggressively progressive, they place great importance on family and frequently engage in reflection on the essence of the self. They prefer rest and meditation, and consistently refine their thoughts with care.
Instead of initiating many new undertakings, they excel at bringing tasks to completion. They also tend to prefer independent research and planning rather than collaborative work with others.

In contrast, the legs are well developed, making this type well suited for long-distance walking.
They tend to process thoughts quickly, and unlike the Taeeum type, which relies more on emotion, they rely more on sensory perception. Their sense of feeling and intuition is highly developed, and they are often associated with relatively higher serotonergic activity.
They are highly sensitive and tend to make judgments based on subtle impressions; however, these judgments are rarely inaccurate, owing to their finely tuned perceptual abilities. With such refined sensitivity, they are capable of achieving precise recognition through feeling alone.
Among the four primary senses, the sense of taste is particularly well developed. They tend to enjoy food deeply, appreciating and discerning flavors with notable subtlety.

12) The Cycle of Nature and Life
The rhythm of nature is fundamentally simple. It is the process in which energy and gravity—that is, the force that expands outward and the force that gathers inward—alternate in dominance over time.
This movement is grounded in the cyclical interplay of Yin and Yang.

Just as a clock spring is wound and then unwound, and as a pendulum swings left and right while continually returning toward its center, the alternating interplay of centrifugal and centripetal forces constitutes the very foundation of life.
If this cycle is disrupted, the phenomena of life cease.
Like a spring that is compressed and then released—again and again—this continuous repetition reflects the principle of Yin–Yang circulation. Within this dynamic process, the distinct phases known as the Five Elements emerge.

The positive extreme of the wave corresponds to the summer solstice, and the negative extreme corresponds to the winter solstice. From the summer solstice to the winter solstice, Yin force operates, much like a clock spring being wound. From the winter solstice to the summer solstice, Yang force operates, like a clock functioning as its spring unwinds. This dynamic is what is represented by the Taiji.
Interpreting various metabolic processes within the human body through this principle of the ascending and descending movements of Yin and Yang, and understanding their differences, constitutes the essence of Sasang medicine. Hormones, electrolytes, and even the autonomic nervous system—such as the sympathetic and parasympathetic systems—are all reinterpreted as forms of energy within the framework of Sasang medicine. These aspects will be addressed in greater detail in subsequent discussions.

13) Clinical Practice and Constitutional Medicine – Medicine Beyond Statistics
Even when the same disease is present, its cause, progression, and treatment approach can differ completely depending on the constitution in which it arises.

Medicine Beyond Statistical Averages
Modern medicine is largely based on statistics. It gathers data from numerous patients, establishes an average, and selects treatments that best fit that average. This approach is effective for many people; however, those who fall outside the average may not benefit, or may even experience adverse effects. In other words, standard treatment inevitably leaves some individuals behind.
Sasang medicine goes beyond this average. It does not regard a person as a single statistical value. Instead, it understands each individual based on their unique balance of Yin and Yang—that is, their inherent energetic structure.

Disease is not viewed as a uniform external enemy, but as the result of an imbalance within the individual. Therefore, treatment is not based on the disease itself, but on the person. Even with the same illness, one constitution may require cooling, while another may require warming. This is the essence of a constitutional medical approach.
If standard medicine seeks a single answer, Sasang medicine seeks different answers for each individual. Ultimately, true treatment is not about conforming to an average, but about restoring the person to their original state. This is the essence of medicine beyond statistics, and of truly personalized care.
Furthermore, Sasang medicine, when combined with modern genetics-based pharmacogenomics—integrating phenotyping and genotyping—has the potential to provide a strong foundation for the advancement of human medicine.
What I propose is that Sasang medicine is not yet a completed system of medicine. However, it offers a macroscopic perspective and insights into constitutional differences that have not been fully observed or recognized in Western medicine, which has traditionally focused on the microscopic, chemistry-centered view. By integrating this macroscopic framework with the extensive microscopic research accumulated in Western medicine—much like assembling the components of the human body into a coherent whole—it may serve as a foundational step toward the completion of a more comprehensive medical system for humanity.

📘 Conclusion
The laws of the universe are unified. The principles that operate in the vast, macroscopic world are repeated in the same way within the smaller, microscopic world.
The application of Sasang medicine can already be observed in modern pharmacogenomics, and in the classification of anticancer therapies, where targeted treatments evaluate the compatibility of specific receptors. The outcomes of such approaches closely parallel the relationship between constitution and therapeutic response described in Sasang medicine.
By integrating these two perspectives, modern medicine can evolve into a more mature and refined system. It will become possible to recognize that many of the side effects observed in the application of Western pharmaceuticals may, in fact, arise from a mismatch between constitution and treatment.
Through more precise and constitutionally aligned use of medications, it will be possible to achieve highly effective therapeutic outcomes.