Yin and Yang, what could the symbol mean?

We see the symbol of Yin and Yang everywhere, from martial arts school flyers to T-shirts and even Traditional Chinese Medicine (TCM) theory, but what does it mean? The world-famous symbol depicts two opposing forces, Yin and Yang, that cannot exist without each other. In fact, they both carry a seed of the other, hence the dots you see in their symbol. Although they are described as in constant struggle, one can only gain temporary dominance over the other and their relationship produces the rhythm of life. Yin aspects include night, coldness and rest, while Yang includes daylight, heat and activity. The concept originates from the I Ching, a fundamental Chinese philosophy work that deals with the cycles of nature.

In TCM theory, health conditions and their precursors commonly have underlying Yin/Yang imbalances as one of their causes. A fever may be considered a Yang excess, while cold limbs is generally classified as too much Yin. The optimal state for every being, sometimes including social and economic systems, is an equal balance between Yin and Yang.

Besides classifying health problems, the Yin/Yang concept may have helped with harvesting herbal medicines too. Some theories suggest that the symbol’s shape comes from the pattern traced by a pole’s shadow length throughout the year. This revealed when the longest and shortest days were, giving an indication as to the best times for planting or foraging. We now know that factors such as sunlight and temperature affect the composition of herbs, so correct timing may be essential for the best results.

Source: https://pdfs.semanticscholar.org/61cd/301ea132d486e76ec85a2355b8f253cba8ad.pdf