 Some controversy exists over the number of souls in a person; for instance, one of the traditions within Daoism proposes a soul structure of "sanhunqipo" ; that is, "three "hun" and seven "po"".The historian Yü Ying-shih describes "hun" and "po" as "two pivotal concepts that have been, and remain today, the key to understanding Chinese views of the human soul and the afterlife" (Yü 1987, 363)

The Chinese characters and for "hun" and "po" typify the most common character classification of "radical-phonetic" or "phono-semantic" graphs, which combine a "radical" or "signific" (recurring graphic elements that roughly provide semantic information) with a "phonetic" (suggesting ancient pronunciation).