Yin and Yang

Origin

The terms Yin and Yang originally described the shaded and sunny sides of a hill. The earliest documented use of the pair as cosmological principles appears in the Yijing or I Ching around 1000 BCE, where the broken line is Yin and the solid line is Yang. The philosopher Zou Yan, who flourished around 305 to 240 BCE, systematised Yin-Yang together with the Five Phases or Wu Xing into the school known as Yinyang Jia. From this school the doctrine entered Confucianism, Taoism, and Chinese medicine, and from there spread to Korea, Japan, and Vietnam.

The classical Taiji symbol, with the curved division and two dots, was first drawn by the Song dynasty philosopher Zhou Dunyi in his Taijitu Shuo, the Explanation of the Diagram of the Supreme Polarity, around 1070 CE. Earlier forms used concentric circles or simple half-circles. Zhou Dunyi's diagram synthesised Confucian, Taoist, and Buddhist cosmology into a single image and became the standard visual emblem of Yin and Yang. The doctrine entered the European intellectual world through the Jesuit missionaries of the seventeenth century and was popularised in the twentieth century by Carl Gustav Jung, Joseph Needham, and the New Age movement.

Meaning and method

Yin and Yang are defined relationally, not absolutely. Anything is Yang relative to something more Yin and Yin relative to something more Yang. The same person is Yang to their child and Yin to their parent. Day is Yang relative to night, but the morning is Yin relative to the afternoon. This relational definition is the foundation of the system's subtlety. The five classical attributes of the pair are: Yin is dark, cold, descending, contracting, material; Yang is light, hot, ascending, expanding, immaterial. From these arise dozens of further correspondences: Yin is moon, water, female, earth, autumn, winter, north, valley; Yang is sun, fire, male, heaven, spring, summer, south, mountain.

The classical Yin-Yang doctrine holds four laws of transformation. First, Yin and Yang are opposed but interdependent: each defines the other. Second, they consume and support each other: when one grows the other diminishes. Third, they transform into each other at their extreme: the deepest night gives birth to dawn, the hottest summer to autumn. Fourth, they contain each other: every Yin holds a seed of Yang, every Yang a seed of Yin, represented by the small dots within the Taiji symbol. These four laws govern the change of seasons, the rhythm of breath, the cycle of health and illness, and the unfolding of every situation.

In practice

In I Ching divination, Yin and Yang are the two basic lines whose combinations build the trigrams and hexagrams. Each hexagram is a configuration of six Yin or Yang lines, and the changing lines (old Yin or old Yang) transform into their opposites, producing the secondary hexagram. The practitioner learns to recognise which forces in a situation are Yin and which Yang, where balance is sought, where imbalance has set in. Use the I Ching oracle to observe the lines in action.

In Chinese medicine, every diagnosis is a question of Yin-Yang balance. A red face, fever, thirst, restlessness, and a rapid pulse signal Yang excess or Yin deficiency. A pale face, cold limbs, low energy, watery stools, and a weak pulse signal Yin excess or Yang deficiency. Treatment, whether by acupuncture, herbs, diet, or exercise, restores balance. In daily life you can apply Yin-Yang awareness by noticing where you are too active or too passive, too giving or too receiving, too speaking or too listening, and correcting toward the middle. Combine with numerology by mapping even numbers to Yin, odd to Yang.

Symbolic depth

Yin and Yang is not a dualism. Western philosophy often poses irreducible opposites: good and evil, spirit and matter, mind and body. Yin and Yang are not irreducible. They emerge together from a prior unity called the Wuji, the limitless, and they return to it. Between Wuji and the world of forms lies the Taiji, the supreme polarity, the moment at which the limitless differentiates into the two principles. The Taiji symbol depicts this differentiation: a single circle that contains its own division, and within each half the seed of its opposite.

In Taoism, the goal is not to choose Yang over Yin or to escape Yin into pure Yang, but to harmonise the two, to flow with their alternation, to live with the wisdom of Wu Wei or effortless action. The same doctrine appears in alchemy as the marriage of sulphur and mercury, sun and moon, king and queen, the conjunction that produces the philosopher's stone. Continue with I Ching, Hexagram, Trigram, Bagua, and Taoism. The wider glossary and oracle hub offer further reading.

Also known as

• Taiji
• Supreme Polarity
• Yin-Yang
• Complementary Opposites
• Dao Polarity