Chapter I
What it means
Yin and yang began as the shady and the sunny sides of a hill. They came to name two forces present in everything: yin is dark, cool, soft, receptive and still; yang is bright, warm, hard, active and moving. Neither exists without the other, and each turns into the other, as night turns into day.
The taijitu draws this in one circle. The two halves curl around each other, and each contains a small dot of its opposite: within yin there is always some yang, within yang some yin. Daoists see the whole circle as the taiji, the “supreme ultimate” from which the world unfolds.
Chapter II
Where it comes from
The ideas of yin and yang are found in Chinese texts of the late first millennium BCE and were developed by thinkers of the Han dynasty into a system that explained the seasons, the body and the state. Diagrams of the taiji were drawn by Song dynasty thinkers, notably Zhou Dunyi (1017–1073). The familiar swirling form became common from the Ming dynasty.
Chapter III
Where you see it today
The yin-yang symbol is seen in Daoist temples, on martial arts uniforms and in Chinese medicine, where health is understood as a balance of yin and yang. It is one of the most widely recognised symbols in the world, used in jewellery, logos and tattoos.