Three Yin and Three Yang Guest-Qi Model Across Time Scales
We now enter the largest, most difficult, and yet most central system in this account of Chinese medical time and space: the higher-order Yin-Yang series known as the Three Yin and Three Yang. The first model is the annual guest-qi variation model of the Three Yin and Three Yang. It can be imagined as a Ferris wheel with six cabins corresponding to the Three Yin and Three Yang, rotating continuously in a clockwise direction. The framework has two versions operating at different temporal scales. Within the broader system of the Five Movements and Six Qi, this model carries the dynamic variable of the principle of constancy and change—the element of change. In the six-year-cycle version, the climatic character of an entire year is governed by Sitian (qi governing Heaven) and Zaiquan (qi at the spring), and this governing pair changes each year. The other version completes one cycle per year. In this version, there are two roles: host qi, representing the host, and guest qi, representing the guest. Guest qi is called “guest” precisely because, like a visitor, it comes and goes and is used to represent anomalous climatic fluctuations from year to year. Within the six segments of a year, the guest qi occupying the first two-month period—the initial qi—jumps to a different position each year according to the year’s stem and branch. By fitting host qi and guest qi together, the ancients attempted to incorporate year-to-year meteorological disturbances attributed to larger celestial scales into a calculable model.
