Yin and yang are the two complementary forces of Chinese philosophy. The words first meant the shady side and the sunny side of a hill. The black and white circle that shows them is called the taijitu, the "diagram of the supreme ultimate."
Two sides of one hill
Yin is the shaded side: dark, cool, receptive and still. Classical sources link it with earth, the moon, water, even numbers and the broken line. Yang is the sunlit side: bright, warm, active and moving, linked with heaven, the sun, fire, odd numbers and the unbroken line. Neither is good or bad. Each needs the other, the way day needs night.
By the 3rd century BCE the pair was the basis of a whole school of cosmology led by Zou Yan.
Yin and yang in the I Ching and Taoism
The Xici, an appendix to the I Ching, or Book of Changes, says: "A succession of yin and yang is called the Tao." The same text traces how things unfold: the taiji, or supreme ultimate, gives rise to yin and yang, which give rise to four images, and those to the eight trigrams.
The Daodejing, the classic of Taoism, puts it in one line: "The ten thousand things carry yin and embrace yang." In the 11th century the philosopher Zhou Dunyi wrote his Explanation of the Diagram of the Supreme Ultimate, which joined Taoist cosmology with the I Ching.
How to read the symbol
An S-shaped line divides it into a dark half for yin and a light half for yang. Each half swells as the other thins: one force waxes while the other wanes. Inside each half sits a dot of the opposite color, the seed of one within the other. Neither exists alone.
The familiar swirl took shape slowly. Zhao Huiqian drew a swirling version, ringed by the eight trigrams, in the 1370s. The dots appeared late in the Ming dynasty and grew common in the Qing. A red and blue version, without the dots, sits at the center of South Korea's flag.
The bagua: eight trigrams around the circle
Each trigram is a stack of three lines, solid for yang or broken for yin. The eight possible stacks stand for heaven, earth, thunder, wind, water, fire, mountain and lake. Legend says the sage ruler Fuxi first saw them in the markings on a dragon-horse that rose from the river, a tortoise in some tellings. Stacked in pairs, they form the 64 hexagrams of the I Ching.
The trigrams are set around the circle in two classic orders: the Earlier Heaven arrangement, credited to Fuxi, and the Later Heaven arrangement, credited to King Wen of Zhou. In feng shui, a bagua mirror is sometimes hung above a door or window that faces a sharp corner or a road leading straight to the house, to turn away what practitioners call "poison arrows." Tradition says never to aim one at a neighbor's home.
Yin and yang in jewelry
On a pendant the taijitu often sits inside an octagon of trigrams, the same layout as the bagua mirror. Some rings rotate, so the trigrams turn around the circle. Matching bracelet sets for couples borrow the idea that two different halves make one whole. You will find the symbol carved in black obsidian and in jade, and more designs in our necklaces and pendants.
