Yin and Yang (阴阳)

The pair that every traditional description is built on — the two modes anything can be in. Yin and yang are not two things but two descriptions of one thing: the shaded and the sunlit side, the still and the active, the holding and the moving. In feng shui, every feature of a site is read by which mode it is in and whether the two are in workable proportion.

It belongs to the classical vocabulary of the tradition. The pair that every traditional description is built on — the two modes anything can be in. The pair is the one concept in the tradition that is explicitly relational — the sources never assign a fixed value to either side, which is why the same feature can be read as favourable or not depending on its surroundings.

The classical method reads a site by its balance: a room that is entirely yin is described as stagnant, one entirely yang as exposed. The tradition's ideal is a proportion rather than an equality, and the sources generally weight yang slightly higher for living space. It is grouped under Earth (土) in the five-element system.