The asymmetric count at the centre of Chinese soul theory, three hun against seven po, is not an arbitrary numerological flourish; it follows the same yin-yang logic that assigns the hun to the lighter, ascending, less numerous category and the po to the heavier, more numerous, earthbound one. Odd numbers were conventionally associated with yang and even numbers with yin in Chinese correlative thought generally, which makes the specific counts, three and seven, both odd, a slightly more complicated case than a simple parity rule would predict, and later commentators and religious specialists offered varying explanations tying the specific numbers to particular deities, body locations or ritual functions rather than treating them as self-evident.
What both counts agree on is a shared structural claim: a person is not unified but genuinely plural, composed of multiple hun and multiple po together, whose harmonious cooperation constitutes health and whose disharmony, excessive wandering by a hun, or excessive heaviness and disorder among the po, constitutes illness or spiritual instability. This plurality is one reason Daoist internal alchemy describes its central task not as strengthening a single soul but as marrying two populations of souls that pull, by their basic yin-yang natures, in different directions.
Later syncretic Chinese religious and medical texts sometimes assign names, colours, associated organs and even individual personalities to each of the three hun and seven po separately, elaborating the basic pairing into a considerably more detailed internal pantheon, evidence of how productive the underlying hun-po distinction proved to be as a framework other Chinese religious specialists kept building on for centuries after its earliest attestation.