A living person in this universe is a composite. Two souls inhabit one body, and they have different natures, different appetites, and different destinations.
The hun (魂) is the cloud-soul: yang, light, clear, intelligent. It is the part that thinks, remembers, loves, and composes poetry. It is associated with breath and with the liver. When a person dies, the hun leaves and goes upward.
The po (魄) is the white-soul: yin, heavy, clouded, dull. It is the part bound to the flesh — appetite, sensation, the body’s sheer habit of continuing. It stays with the corpse.
The classical formula usually gives a person three hun and seven po, and the numbers matter less than the direction: the hun ascends, the po descends with the body into the earth.
Why this explains the monsters
The single most useful thing about the doctrine is that it turns “walking corpse” from a horror trope into a diagnosis.
- While the hun is present, it is the person. A newly dead soul that comes back to settle its affairs — to ask for its mother to be fed, its essays printed, its debts paid — comes back whole: it weeps, it reasons, it says goodbye properly. This is the first half of 《南昌士人》.
- Once the hun scatters, it is not the person. What is left standing in the room is the po wearing a face: the shape without the mind, driven by the body’s last appetites. It cannot be argued with, only outrun or mastered. This is the second half of the same story — the moment the dead man’s eyes go blank and his face begins to spoil.
As Yuan Mei’s commentator puts it: 魂在，则其人也；魂去，则非其人也 — while the hun is present it is the person; once the hun is gone it is not.
What follows from it
Possession and borrowed bodies. Because the soul is not identical with the body, a soul can in principle occupy a different body. 借尸还魂 — “borrowing a corpse to return the soul” — is the standard mechanism, and it is why the resurrected in these stories so often wake in the wrong face, the wrong marriage, and the wrong village. See 《灵璧女借尸还魂》.
Exchanging forms. The same logic has a criminal use. In 《李通判》 a Daoist intends to move his own soul into a rich young man’s body; the trick is caught because the shape emerging from the coffin is the master’s while the voice is the priest’s. Shape and person are separable, and the separation is a technology.
Why the dead need burying. A body with the po still in it is not inert. It can travel — hence the later Hunan legends of the corpse-drivers who marched the dead home over hundreds of miles, and hence the horror of an unburied or disturbed grave.
Why ghosts are cold. The po is yin. Where it concentrates, the temperature drops, and the drop is the first thing a living body notices. In 《骷髅吹气》 the victim measures his own haunting: a cold spot the size of a walnut, then a plate, then half the mat, then into the bone.
The one who can master it
The texts are consistent: 惟有道之人为能制魄 — only a person of the Way can master the po. Not a magistrate, not a soldier, and not courage. It takes someone whose own hun is disciplined enough to out-face a soul that has none.