In Taoism, the concept of a true form (Chinese: 真形 / 眞形; pinyin: Zhēn xíng) is a metaphysicaltheory which posits that there are immutable essences of things — that is, images of the eternal Dao without form.[1][2][3] This belief exists in Chinese Daoist traditions such as the Three Sovereigns corpus, where they emphasise the capacity of talismans, charts, and diagrams to depict both "true forms" and "true names" (真名, Zhēn míng) of demons and spirits.[1] These talismanic representations are considered to be windows into the metaphysical substance of the entities whose "true form" and "true name" they depict.[1] Since both the "true form" and the "true name" of an entity are two sides of the same coin, diagrams and talismans, could serve as apotropaic amulets or summoning devices for the deities the Taoists believed populated the cosmic mountains.[4][1]
Taoists created charts (albums) depicting these "true forms" to help guide them safely through holy places during their pilgrimages, later they created talismans (charms) which displayed these true form charts. A talisman was more easily carried on the person and provided protection for seekers of the Dao as they journeyed into these mountainous areas.
^The I Ching or Book of Changes. Translated by Wilhelm. Princeton: Princeton University Press. 1967. p. 323. Pregadio (“The Notion of Form”), 90–99 explains that the term qi 器, “literally meaning ‘vessel,’ and is used in this sentence as
a synonym of wu [物], ‘thing’; it denotes any entity that exists in the world of form, distinguished from the Dao,
which is above form.”