Oriental medicine is an absolute manifestation of the conventional belief as well as philosophy of East Asia, all founded on specific professed common truth, for instance, the theories of Ki (spelled as 'Qi' in Chinese) and Yin-Yang. To put it differently, in the Orient, medicine, philosophy, art, culture and politics are all founded on a universal perception of the forces as well as cycles of nature.
Basically, the Yin-Yang principle is an ancient Chinese theoretical structure to view as well as understand the world, which, according to Chinese philosophy, was developed during the reigns of the Yin and Chou dynasties between the period 1500 B.C. and 221 B.C. We find the original textual indication about this in the Yi Jing (I Ching), the Book of Changes, sometime in 800 B.C. and it forms the characteristics of change as well as of process that is at its core. In effect, in Chinese philosophy, the Yin-Yang theory forms the basis for comprehending the entire phenomena, especially health and death. In the philosophy of the West, contradicting ideas oppose one another - for instance, if it is night, it cannot be day. Nevertheless, it needs to be noted that, according to Chinese philosophy, although Yin and Yang are opposing, they balance one another. Precisely speaking, Yin and Yang are differing, but they have the aptitude to develop into each other. Besides, Yin and Yang enclose a small portion of one another.
Placing the different elements of the character collectively, Yin is considered to be the shady or cloudy side of the hill, while Yang to be the bright or sunny side. There is light and warmth on the side of Yang and people are active. On the other hand, the shady side of Yin is cold as well as dark where all are taking rest.
Nevertheless, it is not true that the Yin and Yang theory just puts phenomena into permanent classes. On the contrary, it is a method of elucidating dynamic processes. Precisely speaking, both Yin and Yang are relative terms. Therefore, it makes no sense if we talk of Yin without considering Yang - one is incomplete without the other. According to the Taiji sign of Yin-Yang, Yang is portrayed as the white part of the symbol, while the black part is Yin. These two elements twine around one another and pass through one another (interpenetrate). For instance, you will find a black spot in the white part of the symbol, while the black part will have a white spot. There is nothing which can be described as eternally Yin or Yang, but one of them encloses some part of the other. And these are likely to develop in order that one turns out to be the opposite of the other.
It is possible to further divide the Yin and Yang phenomena. For instance, Yang manifests day in comparison to night and it is possible to divide the day into morning and afternoon. In effect, it is further Yang in the morning, when the sun rises, compared to afternoon, when the sun is on its way to set. In this context, we may say that morning is Yang, while Yin manifests afternoon. As morning changes into afternoon, in the same manner Yang changes into Yin and also Yin changing into Yang. It is a continually evolving process as the day turns into night and summer changes to winter. Similarly, our bodies also move and then take rest, we are warm and subsequently become cool; we wake up and sleep, sleep and wake up. Therefore, it may be certainly said that the change from Yin to Yang or the other way, is a cyclic movement.
According to Chu Hsi, a Chinese philosopher, the drawing back of Yang denotes the birth of Yin. However, this does not mean that when Yang has retreated, a Yin, which is separate from it, takes birth. He further wrote that one can consider Yin-Yang as solitary or as twofold. When perceived as twofold, it divides into Yin and Yang; and when considered as single, it is merely a waxing and waning. The Taiji symbol of Yin-Yang shows that Yin takes birth where Yang reaches its crest and the other way around.
Yin and Yang are related to one another in four different ways - they are in opposition to each other; they balance one another; they are able to consume each other; and they can also convert into one another. Apart from this, both Yin and Yang are divisible infinitely.
While the basic reason for any ailment is an imbalance between Yin and Yang, the fundamental principle of Oriental (East and Far-East Asia) therapy as well as that of shiatsu is to fine-tune this balance. Once we are able to comprehend or identify the character of the imbalance appropriately, it is possible for us to initiate the correct measures to adjust the balance between Yin and Yang within the body. Individually, neither Yin nor Yang are adequate to comprehend the exact nature of imbalances, but comprehending Yin and Yang is the first and right step in the direction of appropriate therapy.