Yin and yang are the attributes of two opposite aspects of related things or phenomena in the universe. Yin and yang can be applied to two different things or phenomenon, or to one object or phenomenon with the aspects of yin and yang within it. The original meaning of yin and yang was very simple, referring to places and their position relative to the sun. A place exposed to the sunlight is warm and bright, while a place in the shadows is relatively cold and dim. That is also to say, the side of an object facing the sun pertains to yang, while the side facing away from the sun pertains to yin. So, millennia ago, Chinese philosophers attributed the things or phenomena which are bright and warm to yang, and the things or phenomena which are dark and cold to yin. In looking at the seasons, it is warm in spring and summer and cold in the autumn and winter. Spring and summer are then attributed to yang, and autumn and winter to yin. Taking a day as another example, it is warm and bright in the daytime while cold and dark at night. So, daytime is attributed to yang and night to yin.
By further observation, it was found that the body of an animal or human being can be warmed to withstand cold through exercise and activity. In contrast, when the body is exposed to cold and remains inactive, it will feel cold. So, activity is attributed to yang, and inactivity to yin. Plants grow rapidly under the sunlight, and slower without the sunlight. Therefore, things or phenomena in an active or excited state are attributed to yang, while those that are in an inhibitory or inactive state are attributed to yin. The theory of yin and yang has evolved into a philosophical and abstract concept used to generalize those things or phenomena with opposite aspects. We can say that yin and yang refer to a pair of standards with opposite properties.
The categorization of things or phenomena into yin and yang refers to the particular properties by which the yin or yang attributes of things or phenomena can be determined. Cold and heat are one of the primary pairs of opposites where things with signs of relative cold are attributed to yin, while those with relative warmth are attributed to yang. Motion and stillness form another primary pair of characteristics of which one can determine yin or yang attributes. Something in nature that is relatively active and excited is attributed to yang, while things that are relatively still, inactive or inhibited are attributed to yin. Considering the natures of cold/heat and motion/stillness of, many other yin and yang attributes have evolved over time. For example, yang includes activity, outward movement, ascending, warmth, brightness, dispersing, outside and hyperactivity. Yin features include stasis, inward movement, descending, accumulating, contraction, and inhibition.
|space (direction)||upside, outside, left, south||downside, inside, right, north|
|season||spring and summer||autumn and winter|
|temperature||warm and hot||cool and cold|
|motion||dispersion, ascent, activity||accumulating, descent, inactivity|
|action||exiting, activity, qi transformation||inhibiting, decline, formation|
Again, it must be noted that the theory of yin and yang does not refer to concrete things or objects, but that yin and yang are abstracted concepts concerned only with properties. Many phenomena or objects are not related nor have opposite qualities, and for practical reasons there is no need to divide or compare them into yin or yang. For example, the couch in a living room has no relationship with the house across the street and so there is little reason to call one more yin or yang than the other. i
Lao Zi said, “All things embrace yang and carry yin.”
Yin and yang have both relative and absolute aspects. For example, regarding water and fire, water pertains to yin and fire to yang. Water, no matter how hot, it is always yin when compared with fire. Fire, no matter how weak, always belongs to yang when compared with water. The yin and yang attributes are fixed, and thus absolute.
Because the qualities of things naturally change, things with yin and yang attributes also change over time. Therefore, the yin and yang attributes of things can be absolute, but also relative. The relative attributes of yin and yang manifest in three ways:
The first of the relative attributes is the mutual transformation of yin and yang. Under certain conditions, the yin and yang attributes of things may change into their polar opposites. A bright flame will eventually burn out and become cold. A night will always turn back into day. In the clinic, we see that when the cold or heat nature of a disease changes, the yin or yang attribute of the condition will also change. For example, a common cold caused by what Chinese medicine calls “wind-cold” has manifestations that include physical coldness and a whitish coating on the tongue. Both of these are signs of cold, which is yin. If treatment is delayed, then the cold pattern may turn into a heat pattern with manifestations that include fever with a yellow coating on the tongue. In this case we can observe that a yin-type condition has transformed into a yang-type condition. Conversely, it is also possible for a heat condition to transform into a cold condition.
Many Chinese books and their translations will refer to yin “belonging to”, “pertaining to”, “refers to” or is “associated with” substance, immobility or a quality of cold, etc. As another example, wood is “associated with” wind. For the student (perhaps especially for those used to the relative precision of the English language) this may seem frustratingly vague. Such language is used because in Chinese philosophy, things of the world are not objects of certainty, but rather things with qualities; these are things known only through their appearance at particular times and places. (Astute readers may note the similarity of this thought to some concepts described by modern quantum physics.)
The reasons for this outlook go back to ancient Asian philosophy (codified in Taoism) which states clearly that “the Tao that can be spoken (or named) is not the true Tao”. Only the Tao itself is complete. Yin and yang, the five phases, and indeed all the medical processes of the body thoroughly discussed in this and countless other books are only reflections and “manifestations” of the oneness of the Tao.
The second relative attribute is that yin and yang are said to have infinite divisibility. Two things that are related yet contrary can be further divided into yin and yang; in other words, the yin or the yang aspects themselves can also be divided into another pair of yin and yang, and this kind of subdivision can be continued infinitely. However, each yin and yang aspect always includes the other aspect, so they will never be completely yin or completely yang. Within any yang object there is a yin–aspect, called the “yin within yang”. A yin object also contains a yang-aspect within it, called the “yang within yin”.
The yin and yang attributes of things or phenomena are determined according to the proportions of the yin or yang components. For example, if one thing or phenomenon pertaining to yang contains a small yin component, its general attribute still belongs to yang. Our basic example of day and night is informative. The daytime is yang because it is active and bright and warm. Yet, as it declines into night we have aspects of yin. The late afternoon is called “yin within yang”. Night time is yin and falls deeper and deeper into yin. This period of dark is called “yin within yin.” Yet as the night reaches its darkest, it can go no farther into yin and thus its movement changes in the direction of yang (the morning). The latter half of the night is therefore called “yang within yin”. The morning signifies the full beginning of the new day as the sun rises to its zenith, so the morning is therefore called “yang within yang”.
i To analyze the yin and yang attributes of two things or phenomena, two conditions must be met. The first condition is that these things or phenomena have some correlation or defined relationship with each other. Second, these two things or phenomena must in some way be in opposition to each other. Therefore, only two related yet opposite things or phenomena or two opposite aspects within one thing or phenomena can be generalized and analyzed with attributes of yin and yang. For example, cold and heat, both of which are used to describe temperature and are opposite in nature, can be symbolized with yin and yang. If two things or phenomena do not correlate to each other, or they are correlated but their features are not opposite, they cannot be explained with yin and yang. For example, ice and snow, both of which are the crystal transformed from water, do not have opposite features, so their relationship cannot be as easily described with yin and yang.