Sitian, Zaiquan, and the Climate of the Upper and Lower Halves of the Year

The Waijing Weiyan states that the qi of Heaven and Earth are constantly interacting: Heavenly Administration (si tian) broadly governs the upper region, while Terrestrial Effect (zai quan) broadly governs the lower, but the two should not be cut apart as completely separate halves.

This version is more consistent with a continuous model of Heaven–Earth interaction. It also provides the rationale, within this framework, for why the flavors or properties of substances arising from Earth may vary according to the annual zai quan condition.

A close reading of disorders associated with si tian and zai quan in the Zhi Zhen Yao Da Lun suggests another pattern: si tian disorders tend to concentrate above the navel, treated here as the boundary of Heaven–Earth qi-interchange; zai quan disorders tend to concentrate in the lower burner and the limbs, or may reach the upper burner when qi surges upward.

The following summary from the Waijing Weiyan may be used as a reference:

Treating disorders of Heavenly Administration: pathogenic influence is received from above; disease is more often seen in the Heart and Lung, the channels and collaterals, and the qi level.

Treating disorders of Terrestrial Effect: pathogenic influence is received from below; disease is more often seen in the Liver and Kidney, the uterus/reproductive network, and the blood level.