YIN-YANG THEORY
INTRODUCTION
According to ancient Eastern philosophy, everything in the universe can be represented by the dynamic interaction between two opposing and complementary principles, described as Yin and Yang. This is probably the most important concept applied in Traditional Chinese Medicine, where all pathophysiological and therapeutic elements can be analyzed from the perspective of Yin-Yang.
Its origin traces back to the ancient Chinese sages, through careful contemplation of natural phenomena. In this theory, everything that has an expansive, dynamic, bright, clear, warm, ascending, masculine, and functional nature relates to Yang. On the other hand, what presents a retracted, static, opaque, dark, descending, feminine, and structural nature belongs to Yin. Since all things are composed of a fundamental principle called Qi or Chi (which means energy or vital fluid), everything can be summarized in different states of Qi, more precisely Yang Qi and Yin Qi.
YIN-YANG SYMBOL AND ITS ASPECTS
Ancient Chinese scholars concluded that human beings are a representation of the universe in which they live and, consequently, can also be analyzed according to the concept of Yin-Yang. Thus, in the human body, the dorsal side, the region above the waist and the posterolateral part of the limbs, the superficial level (cutaneous and muscular), the hollow viscera (Fu), organic function, and Qi belong to Yang. Meanwhile, the ventral side, the region below the waist and the anteromedial part of the limbs, the deep level (organic), the solid organs (Zang), blood, and fluids belong to Yin.
FUNDAMENTAL CONCEPTS OF YIN-YANG THEORY
Opposition of Yin and Yang
They represent opposing phases within a cycle or opposing stages of matter.
Interdependence of Yin and Yang
Yin does not exist without Yang, just as Yang does not exist without Yin.
Mutual consumption inversely proportional
The increase of one decreases the other, in a quest for dynamic balance.
Intertransformation of Yin and Yang
At a certain stage of development, one converts into the other.
YIN-YANG AND THE 24-HOUR DAILY CYCLE
The intertransformation of Yin and Yang becomes evident, for example, when we observe natural phenomena. Taking the daily cycle as an example, when the sun rises, the day (Yang) begins. However, to reach the maximum heat of noon, Yang needs to increase. Thus, the morning corresponds to Yang within Yang. From noon, when Yang has reached its maximum, Yin gradually begins to grow, and Yang progressively decreases, but it is still day. Therefore, the afternoon represents Yin within Yang. When the sun sets, night (Yin) begins. However, to reach the maximum darkness, Yin needs to increase. Consequently, the nighttime period occurs with Yin within Yin. Finally, for dawn to arrive, Yin needs to decrease and Yang to increase, but it is still night (Yin). Thus, the early morning corresponds to Yang within Yin, and the cycle repeats.
YIN-YANG AND THE SEASONS OF THE YEAR
The mutual transformation of Yin and Yang can also be observed in the seasons of the year, where the peak of Yang Qi occurs at the summer solstice and Yin Qi is at its lowest level. From there, a gradual decline in Yang is observed, and Yin begins to progressively grow, starting to predominate after the autumn equinox. Yang continues to decrease, and cold reaches its maximum at the winter solstice. Now it is time for Yin to start decreasing, and Yang resumes its growth, beginning to predominate after the spring equinox. Yin continues to decrease until the summer solstice arrives, and the cycle repeats.
YIN-YANG AND ITS APPLICATIONS IN HEALTH
For Traditional Chinese Medicine, all signs and symptoms are ultimately derived from the imbalance between these two principles. Let’s look at some examples:
In human health, the interaction between Yin and Yang can be seen both from a physiological and a pathological perspective. Physiologically, the mutual consumption of Yin and Yang ensures the balance of physiological functions. This process can be observed, for example, in the sleep-wake cycle, thermal regulation, regulation of heart rate and respiration, fluid replenishment and elimination, etc.
Pathologically, the excessive increase of one aspect can lead to the consumption of the opposite quality, or the consumption of one aspect can lead to an apparent increase of the other, as illustrated below:
The treatment by Traditional Chinese Medicine basically boils down to:
Tonifying Yin
Tonifying Yang
Correcting excess Yin
Correcting excess Yang
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