Yin and Yang is the simplest concept used by the ancient Chinese to understand the universe. It means, very simply, that everything in the universe has two opposite sides. Yin and Yang are nothing but a pair of words used to express and understand this simple pattern of nature.

Yin originally meant ‘shade’; Yang, ‘sunlight’ or ‘brightness’. There is great contrast between these two things, therefore they are opposites, since there are only two possibilities.

If we look at John and Mary, the simplest way to describe them is through pairs of opposite words. For instance, Mary is taller than John. John is male, Mary is female. Mary has a dark complexion, John has light skin. There are similar pairs of concepts everywhere: day and night, hot and cold, summer and winter, damp and dry, soft and hard, north and south, sun and moon, alive and inanimate, back and front… the list goes on forever.

Although Yin and Yang are opposites, they are also interdependent; one cannot exist without the other. Without the concept of ‘short’, how could there be the concept of ‘tall’ to contrast it with? Without woman, there can be no man; without north, south would have no meaning. Everything in the universe is thus two-sided.

Many people’s vision stops at one side, however. Eating a lot of raw vegetables increases the intake of vitamins and nutrients, but what is the downside? When a country’s Gross Domestic Product increases dramatically, wealth increases dramatically – but what is the downside? Investing in mutual funds is likely to provide the highest return, but what is the downside?

Yin and Yang are never static. Yin changes to Yang and Yang changes to Yin. If you throw a ball up in the air, it rises to its highest point then falls back down. Winter slowly changes to summer. Day changes to night. Economic expansion changes to economic contraction. Interest rates change from high to low. A centrally controlled market economy changes to a free market economy. High crime rate changes to low crime rate. Cold chills change to fever. Constipation changes to diarrhea. Peace changes to war. Enemies become friends. Water changes to vapor.

The transformations never stop. After winter changes to summer, summer changes back to winter. After day changes to night, night changes back to day again. After each economical expansion changes to contraction, the contraction eventually changes back to expansion.

The application of Yin and Yang is not limited to one or a few fields; it covers everything in nature. The beauty is that one can describe anything using only two opposite concepts. That is why Yin and Yang is the simplest law of nature. Of course, this pattern was recognized not only by the ancient Chinese; many other cultures have a similar understanding of this pattern. The Chinese call it Yin and Yang, but you can call it Left and Right or Bright and Dark or anything you like. After all, it’s just a pair of contrasting words.

–Dr. Thomas Zhang