In Taoism, the concept of a true form () is a metaphysical theory which posits that there are immutable essences of things â that is, images of the eternal Dao without form. 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" () of demons and spirits. These talismanic representations are considered to be windows into the metaphysical substance of the entities whose "true form" and "true name" they depict. 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.
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 as they journeyed into these mountainous areas.
During the medieval period () Taoists developed the idea of the "true form" or . The term "true form" denotes the original form something has as a part of the , which Taoists refer to as the , and can be applied to a broad range of things such as a deity, an icon, a purified self, a talisman, or a picture. Essentially, talismans and diagrams were depictions of a supramundane entities, and gave a visually observable shape to the metaphysical substance of a supramundane being's "image", which they referred to as the . Taoists believe that the "true form" or name of a spirit inscribed on a talisman is legible only to supernatural beings, and being in possession of such a talisman gives a sort of temporary "control" over the entity whose name or form is possessed. The names of the entities were typically written in celestial script (), a type of divine talismanic writing, pm a support medium per the instructions provided to the talisman maker in conventional Chinese characters. Once the talisman was reproduced it had to be activated through rituals allowing them to control the associated entities.
Taoists view the "true form" as the inner, often invisible, and formless quality of an entity which they contrast with the outer, visible, and concrete form of the entity. As a key concept behind Taoist visuality, "true forms" are not static and to gain the ability to see these underlying and secret phenomena entails an active journey. Taoist practitioners claim that being able to see "true forms" requires the person to rigorously meditate and visualize and receive spiritual revelation, which requires both practice and have a lot of religious discipline.
"True forms" serve as the parent concept for related Taoist notions such as , , , , and .
According to Dutch Sinologist Kristofer Schipper the concept of "true forms" is the central unifying concept uniting both Taoist art and rituals.
Other than Taoists, Chinese Buddhists have also adopted "true forms", and the related concept of , into their practice.
In order to visualize "true forms" medieval Taoists developed what they called . These true form charts are typically aniconic diagrams organized in a puzzling configuration depicting mountain-inspired paradises (such as grotto-heavens), sacred sites, and (hells). They are classified by Guo Ruoxu () as and in the they are classified as "Numinous Charts". Taoists believe that true form charts and talismans have the power to uncover the "true forms" of the spirits, demons, and numinous entities that inhabit the world, as well as places such as mountains. Taoists used these "true form" charts both for communication and for protection. Regarding their protective function Ge Hong stated: "Having the Album of the True Forms of the Five Marchmounts in your home enables you to deflect violent assault and repulse those who wish to do you harm; they themselves will suffer the calamity they seek to visit upon you." indicating that being in possession of a true form chart can keep its owners safe from potential harm.
According to professor Shih-Shan Susan Huang () true form charts are deliberately designed to be incomprehensible for ordinary people as they are a part of the esoteric teachings of Taoism and can only be read by those who are trained to do so. Taoist rituals have a prominent place in their visual culture and vice versa, with the more esoteric true form charts representing an "outer" ritual dimension that can transform the "inner" experiences. On this Ge Hong commented that during the Eastern Wu dynasty a man by the name of Jie Xiang () was able to read the talismanic script and tell whether it was authentic or inauthentic. Ge Hong claimed that if someone attempted to test him by removing the captions from any therapeutic or apotropaic talisman that Jie Xiang could still tell what was written in them and that he was even able to correct some mistakes in them. However, after Jie Xiang nobody has been able to read the talismanic script meaning that it was impossible to tell if they were right or wrong.
Taoists typically regard the and the as the two most important true form charts. These charts (albums), which contained images that took the form of esoteric mountain landscapes seen from a bird's-eye view, provided their users with guidance and protection needed during travels through the sacred areas. True form charts symbols are related to the configurations found in , Chinese calligraphy, traditional Chinese medicine, and traditional Chinese cartography.
The True Form Chart of the Man-Bird Mountain () is usually regarded by scholars as a type of or a . Researchers generally regard this chart as a combined map of an "immortal mountain" (), or "fairyland", with theological and geographic significance. Some scholars directly regard the True Form Chart of the Man-Bird Mountain as the Kunlun Mountains, believing that the "Kunlun Mountain is the Man-Bird Mountain or Spirit-Bird mountain, and the mother of birds is the Queen Mother of the West". However, scholar Cai Linbo concludes that rather than it being a map, like many true form charts, the True Form Chart of the Man-Bird Mountain is actually a description of the mechanism of the