A few terms you’ll run across in your study of Taijiquan: wuji, taiji, yin, and yang. Briefly, here’s what they are referring to.
Wuji: no extremities, uniform, non differentiated, no opposition
Taiji: grand ultimate, great extreme, differentiation through opposition; the pivotal force that changes wuji into yin and yang, or yin and yang back to wuji. Or as Wang Zongyue allegedly said: “What is Taiji? It is generated from Wuji, and is a pivotal function of movement and stillness. It is the mother of Yin and Yang. When it moves it divides. At rest it reunites.”
Yin & Yang: complimentary opposites. Generally, things that are considered yin include dark, down, less, small, inner, cold…the shady side of the hill. Considered yang include light, up, more, big, outer, hot…the sunny side of the hill. But, it’s all relative. A temperature of 50° is considered yang when compared to freezing, yin when compared to boiling. Your belly would be considered yang when compared to your feet, yin when compared to your head. Unless you were upside down.
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The diagram at the right is often referred to as a “yin yang symbol” or something along those lines. It’s actually called the Taijitu, or taiji diagaram.
One interpretation of the diagram: the circle represents wuji, the white represents yang, black represents yin, and the ‘S’ curve that separates them represents taiji.
These ideas can be experienced at the beginning of most Taiji solo forms. For instance, the Yang style barehand solo form starts with the body in a relaxed, neutral position – mind clear, breathing natural (wuji, or no extremes). From there, the two hands rise, as high as the shoulders. The movement itself could be considered yang (rising, extending…). And the reason, decision, or instigation to move…taiji (the pivotal force that changes wuji…). Arms lower, body sinks – the movement changing from yang to yin.