laoxinglin 老杏林

First Principles 基础

Yin and Yang 阴阳

“Everyone knows the symbol; almost no one was told what it's for. It is not good versus evil. It is the shaded side of the hill and the sunny side — of the same hill.” — Lao Xinglin

Start with the hill

The characters themselves are the best teacher: 阴 yin was the shaded north slope of a hill, 阳 yang the sunlit south slope[1]. Same hill. The shade is not evil, the sunlight is not good; they are two faces of one thing, defined entirely by each other, trading places as the sun moves. Everything else about yin-yang is that image, generalized.

So: cool, dim, still, inward, substantial, resting — the shaded slope — is yin. Warm, bright, active, outward, energetic, transforming — the sunny slope — is yang. Night and day, winter and summer, rest and exertion, the body's moist tissues and its metabolic fire.

The four rules of the relationship

  1. Opposition — each restrains the other, the way night cools the day.
  2. Interdependence — neither exists alone; there is no shade without

sun. Activity is fueled by rest; rest is given meaning by activity.

  1. Mutual transformation — each becomes the other at its extreme, as

midnight turns toward dawn. The symbol's two dots say exactly this: a seed of each inside the other.

  1. Waxing and waning — the balance is a live negotiation, never a

settled score[1].

What medicine does with it

Chinese medicine uses the pair as a first sorting of any pattern: is this condition running hot or cold, over-active or depleted, surface or deep? A flushed, restless, feverish picture reads yang-excess; a pale, cold, exhausted one reads yang-deficient; night sweats and dry heat suggest yin too depleted to anchor the fire[1]. The words are a clinical shorthand — a way of saying which direction the body has tipped — and treatment, in herbs or needles, is described as tipping it back.

That is the whole trick, and it is a good one: not a metaphysics you must believe, but a language for balance you can watch working — on the hill, in the day, in yourself.

Where to next

Yin and yang describe the tilt of a pattern; qi is the tradition's word for what does the moving. Read them together and most of the herb pages on this site begin to make sense.

References

  1. Kaptchuk, The Web That Has No Weaver: Understanding Chinese Medicine, 2nd ed., McGraw-Hill, 2000. ↩

Lao Xinglin seal Reviewed 2026-08-25