What is Yin and Yang in Traditional Chinese Medicine?

The core of Chinese philosophy lies in the concept of Yin and Yang, where "Yin" represents matter and "Yang" represents energy. This concept reflects a universal truth: all living things in the universe engage in a constant transformation between matter and energy. According to Chinese philosophy, this ongoing transformation is the interplay of Yin and Yang.

Taking Earth as an example, our essential energy comes from the sun, which transmits energy to Earth through light and heat. The Earth absorbs this light and heat and, through processes like photosynthesis and other natural laws, transforms them into plants, animals, minerals, and more. Earth's rotation and orbit around the sun create climates that facilitate the absorption of solar energy, converting it into various forms of matter, such as food and minerals, which store the concentrated energy from the sun.

Humans utilize these materials by consuming or using them, releasing the stored energy to sustain bodily functions and maintain societal operations. This framework of understanding not only highlights the practical applications of Yin and Yang philosophy but also underscores a profound relationship between life and the natural world, where energy and matter continuously convert into one another, sustaining and evolving life on Earth.

The saying "All things grow with the sun" reflects the idea that all life on Earth, including our own existence, depends fundamentally on the sun, which provides energy—not material—to the Earth. In the context of Yin and Yang, the sun's energy, manifesting as light and heat, is considered "Yang". When this energy is stored and converted into matter, it becomes "Yin". Further evolved into plants, animals, and minerals, "Yang" represents the directly usable energy, while "Yin" represents the storage units that condense this energy into tangible, but not directly usable, material forms. To be utilized, these "Yin" forms must be transformed back into "Yang". As an energy entity, "Yang" also needs to be attached to "Yin" for preservation. Thus, the "Dao De Jing" states: "All things carry Yin and embrace Yang; they achieve harmony by blending these forces." This implies that all living beings exist by utilizing "Yin" as a carrier, enclosing an energy entity within. Upon closer consideration, this description applies universally, especially to humans, who are a tangible embodiment of "Yin-Yang interaction", encompassing a physical body filled with energy. If the transformation between Yin and Yang continues smoothly, life remains healthy; if not, life ceases. This principle underscores the essential, dynamic balance that sustains life.

In the human body, "Yang" represents the directly usable energy. For example, movement requires energy consumption, which is considered Yang, also referred to as "Qi". The ability to see with the eyes, hear with the ears, taste with the mouth, the need for energy to absorb and digest food, and maintaining sufficient body temperature for physiological activities—all these physiological functions that consume energy fall under the category of "Yang". Additionally, elements like blood, various body fluids, secretions, hair, bones, and muscles, which are the tangible aspects of the body, belong to the category of "Yin". Chinese philosophy embraces the principle of "simplifying the great way", suggesting that despite the complexity and diversity of all things, their essence lies in the transformations of Yin and Yang. No matter how complex our activities are, their essence involves the changes and transformations of Yin and Yang. Thus, the "Su Wen·Yin Yang Li He Lun" states, "Yin and Yang, in their extremes, can be counted to ten, extended to a hundred, a thousand, or even ten thousand; though vast and countless, their essence is singular." This means that all changes fundamentally adhere to the transformations of Yin and Yang.

The ancient sages of China highly summarized the essence and laws of Yin-Yang change in a classic known as the "I Ching" or "Book of Changes". It is said that "continuous change is called 'change'", where "change" refers to the transformations and transitions of Yin and Yang. The pictograph of the character "易" (Yi) consists of a sun above and a moon below, symbolizing the concept of Yin and Yang. The "I Ching" has always been revered as the foremost classic of Confucianism, ranked at the top of the "Four Books and Five Classics". The version of the "I Ching" we see today was introduced and commented on by Confucius, the founder of Confucianism, who remarked that if one could understand the "I Ching" early in life, they would make no major mistakes.

From another perspective, the world we perceive has aspects that are tangible and directly perceptible, such as physical matter, and aspects that are active but not directly perceptible, such as energy, magnetic fields, emotions, and moods. In Chinese culture, the manifested, tangible aspect is referred to as 'Yin', while the intangible, yet influential aspect is called 'Yang'.

David Bohm, a Nobel laureate in physics, believed that the universe manifests itself in three interwoven aspects: matter, energy, and meaning. Although the world appears complex, everything ultimately involves a continuous transformation between matter and energy. Chinese philosophy refers to this as the constant transformation of Yin and Yang. Mr. Yu Qiuyu once remarked that the Taiji diagram of Yin and Yang is the totem that best represents Chinese culture. This totem reflects the universal law of transformation between Yin and Yang, applicable to all things.