While "yin" would be dark, passive, downward, cold, contracting, and weak, "yang" would be bright, active, upward, hot, expanding, and strong. The shape of the yin and yang sections of the symbol, actually gives you a sense of the continual movement of these two energies, yin to yang and yang to yin, causing everything to happen: just as things expand and contract, and temperature changes from hot to cold.
Yin originally meant "shady, secret, dark, mysterious, cold." It thus could mean the shaded, north side of a mountain or the shaded, south bank of a river. Yang in turn meant "clear, bright, the sun, heat," the opposite of yin and so the lit, south side of a mountain or the lit, north bank of a river. From these basic opposites, a complete system of opposites was elaborated.
Yin represents everything about the world that is dark, hidden, passive, receptive, yielding, cool, soft, and feminine.
Yang represents everything about the world that is illuminated, evident, active, aggressive, controlling, hot, hard, and masculine.
Everything in the world can be identified with either yin or yang. Earth is the ultimate yin object. Heaven is the ultimate yang object. Of the two basic Chinese "Ways," Confucianism is identified with the yang aspect, Taoism with the yin aspect.
Although it is correct to see yin as feminine and yang as masculine, everything in the world is really a mixture of the two, which means that female beings may actually be mostly yang and male beings may actually be mostly yin. Because of that, things that we might expect to be female or male because they clearly represent yin or yang, may turn out to be the opposite instead.
Taoism takes the doctrine of yin and yang, and includes it in its own theory of change. Like Anaximander and Heraclitus, Taoism sees all change as one opposite replacing the other. The familiar diagram of Yin and Yang, the "Great Ultimate" [Wade-Giles T'ai-chi] diagram, shows the opposites flowing into each other. The diagram also illustrates, with interior dots, the idea that each force contains the seed of the other, so that they do not merely replace each other but actually become each other. (The earliest attested example of the diagram, strangely enough, occurs on a Roman shield.)
When it comes to the five elements, earth, water, and wood are clearly to be associated with yin. Water, the softest and most yielding element, becomes the supreme symbol of yin and the Tao in the Tao Te Ching. Fire (the hottest element) and metal (the hardest) both are associated with yang. Nevertheless, the Blue Dragon that symbolizes wood is a principal symbol of yang, while the White Tiger that symbolizes metal is a principal symbol of yin. This kind of reversal turns up frequently in the I Ching.
The opposites can be classified in general as "firm" or "fixed" and "soft" or "fluid." Following are some sets of opposites, listed with the Yin (passive) aspect first, followed by the Yang (active) aspect:
- Unity ~ Diversity
- Realization ~ Potential
- Actuality ~ Perception
- Masculine ~ Feminine
- Mundane (Natural) ~ Divine (Supernatural)
- Dark ~ Light
- Defined ~ Undefined
- Matter ~ Energy
- Stasis ~ Change
- Creation ~ Creator
- Integrity ~ Compromise
- Silence ~ Intercourse
- Death ~ Birth
- Harmony ~ Conflict
- Peace ~ Tension
- Despair ~ Hope
- Acceptance ~ Challenge
- Science ~ Art
- Structure ~ Process
- Waking ~ Dreaming
- Conscious ~ Unconscious
- Reason ~ Intuition
- Consistency ~ Spontaneity
- Day ~ Night
- Destination ~ Journey
- Music ~ Lyric