The characters appear on oracle bones as weather and sunlight. The first dictionary, Xu Shen's Shuowen jiezi around 100 CE, defines yin as darkness, the south bank of a river, the north side of a mountain, and yang as brightness, the south side of a mountain. The Shijing has the pair together: viewing the scenery at a hill, looking for yinyang. The terms describe a slope at a moment: one face lit, one face shadowed, and the light moves. The famous fish diagram arrived much later, popularized by the Song philosopher Zhou Dunyi.
The good-versus-evil reading is a Western retrofit, dualism imported from Persian and Christian frameworks onto a symbol that contains none: the dots in each half encode that every phase carries the seed of its opposite, spring is already inside winter. The balance reading is nearly as wrong: the symbol models rhythm and transformation, not static equilibrium. A hill is not balanced; it is being lit and unlit on schedule.
The claim: the modern balance misreading is load-bearing for hustle culture, you must hold career and rest in perfect static equilibrium, a standard that manufactures guilt, while the original model licenses seasons: the Dao is reading which side of the hill you are on, not standing at the ridge. Verdict: the rhythm reading is the older one, and the burnout critique lands. But the symbol's genius is that it survives its misreadings: even balance-believers get the dots, and the dots are the whole argument.
Why did the West import the symbol and lose the slope?