At their most basic, yin and yang represent a simple duality of opposing phenomena, and are most easily understood by considering some simple physical properties where yin corresponds to qualities such as soft and cold, and yang to qualities such as hard and hot. However, this simple dualism is only a superficial interpretation of yin and yang, which upon further consideration turn out to be much deeper concepts.
The yin and yang symbol shown above, or more properly, the taiji or grand ultimate, consists of a circle with black and white halves divided by an s-shaped line. At the top yang, as represented by white, dominates, while at the bottom yin is preponderant. Each half also contains a small circle of the opposite color at the place where it is fullest.
Each aspect of the taiji is loaded with meaning. First consider the curved line, which divides the circle into two equal but unevenly distributed parts. The equal use of space suggests balance, while the uneven distribution suggests a dynamic interplay of complementary qualities. Yang actively displaces yin, while yin efforlessly flows into the void that yang leaves behind in a process of perpetual interaction and change. Taken together, the even distribution of black and white coupled with the curved-line suggests that balance itself is continually in flux, and that what was once balanced can cease to be so.
Imbalance gives rise to a different type of change and is represented by the smaller circles, which show that where either yin or yang become extreme, a latent aspect of the other resides and can spontaneously emerge. Consider the case of a candle that is beginning to burn out, the flame of which burns brightest just before it is gone. Here as yin begins to dominate, yang appears briefly before the entire candle is extinguished. Similarly when walking, extremely large steps result in overexertion and are contrary to quick progress, which is a case of excess yang leading to yin. Both of these cases show how extremes tend toward instability and can take on characteristics of their opposite.
The small circles are also a statement of how a weakness can become a strength or a strength a weakness under changing circumstances. Consider the case of someone who through working has developed large strong hands. This person will find it hard to thread a needle, while conversely the person with delicate hands used to intricate work will find it hard to perform manual labor. What is useful and appropriate, or not, is highly circumstantial.
An often neglected part of the taiji, is the circle itself. Alone it represents the one, or simply the Tao. But to identify the circle, is to identify both what is and what is not the circle. Thus one gives rise to two, what is and what is not. However, to identify what is and what is not, implies some criteria that distinguishes them. Thus two becomes three – what is, what is not, and the relationship that separates them, and we are back to the curved line separating yang and yin. Then ultimately to define something is also to define what it is not, and to implicitly define the quality that relates the two, and so together the three are parts of an interdependent whole.
One way to interpret this is as a statement of a simple phenomenological truth concerning the limitation of human attention. For example, you think of a tree. Perhaps it’s a specific tree, or maybe some abstract notion of a tree. It doesn’t matter, your conception of tree is what is, and regardless of your conception, it neglects far more than what it conceives. Consider just the leaves. But now the tree is gone. Or consider the tree and the leaves together, and there is still much that is beyond your conception. What of the roots? What of all the things that are not trees? So you consider the universe of all things, but you lose track of the detail. Focusing on some detail, the vastness dispurses. This is the fundamental limitation. What is, or in other words, what can be attended to at any instant, is an infinitesimal bit of what encompasses all of creation, but what is not, is limitless and incomprehensible.
So then the taiji is a reminder that what is not, or in one word, yin, is an infinite source from which to draw. However, because it is outside of our attention, the yin is simultaneously nothing, and yin being yin, it does not force itself upon us, but remains latent until an appropriately receptive vessel emerges for it to fill. So by shifting our perspective of what is, or simply by relaxing and not clinging to what is, we open ourselves to aspects of what is not. This is the basic potential of existence, the salient aspect of which is that there is always something beyond what is that can be drawn from.
Another way to think about the triad above is with respect to the qualities of things. For example, to call something hot is to implicitly define what constitutes cold and to define a scale for differentiating them. But to say that ice is cold implies a very different thing from saying that space is cold. In some sense the meaning of words, especially adjectives, are inherently tied up in their opposites and thereby some scale of comparison. This scale of comparison is rarely made explicit, and while it is typically clear from context, it is also the case that people bring their own distinct scales to words, and the implicit nature of this seems to be a significant cause for miscommunication and misunderstanding.
A few simple interpretations of the taiji symbol have been considered herein, but this brief discussion barely scratches the surface. The concepts of yin and yang have a vast range of application and a myriad of manifestations. Indeed anywhere a relationship between distinct objects or qualities exists, the concepts of yin and yang can provide a potentially useful means of interpreting the nature of that relationship. However when considering any relationship we make a mistake when we fixate solely on this or that because yin and yang are not a matter of this or that, but an acknowledgement that there is a little of this in that and a little of that in this, and that change is always changing.