Where the hun are described as ethereal and volatile, the po are their structural opposite in the classical Chinese scheme: yin rather than yang, heavy and corporeal rather than cloud-like, and conventionally counted as seven, the qipo, rather than three. The po are associated with the body's physical vitality and its appetites, the sensations, drives and reflexes that keep an organism functioning at the level of raw survival rather than the reflective, wandering consciousness attributed to the hun.
Within correlative cosmology, the po are linked to the lungs and to metal among the five phases, an association that, like the hun's link to the liver and wood, was treated as medically consequential rather than merely symbolic: respiratory disorder and disturbances of the po were understood as connected, and treatment could target either. Sudden fright, a common concern in traditional Chinese medical writing, was sometimes explained as a disturbance to the po specifically, distinct from the disturbances attributed to the hun.
At death, the po do not ascend as the hun are said to; they remain with the body, sinking toward the earth and the grave, which is the direct cosmological basis for the entire apparatus of ancestral tomb offerings and grave-based ritual in Chinese religious practice. A hun addressed through spirit tablets and ancestral altars in the home, and a po addressed through offerings and maintenance at the physical burial site, together made up a complete programme of care for the dead, each soul-type requiring its own distinct kind of ongoing attention.