Hun and po are types of souls in Chinese philosophy, traditional medicine and religion. Within this ancient soul dualism tradition, every living human has both a spiritual, ethereal, yang soul which leaves the body after death, and also a corporeal, substantive, yin soul which remains with the corpse of the deceased. Some controversy exists over the number of souls in a person; for instance, one of the traditions within Daoism proposes a soul structure of (), i.e., "three and seven ". The historian Yü Ying-shih describes and as "two pivotal concepts that have been, and remain today, the key to understanding Chinese views of the human soul and the afterlife".

Characters

Like many Chinese characters, and are "phono-semantic" or "radical-phonetic" graphs combining a semantic radical showing the rough meaning of the character with a phonetic guide to its former pronunciation in Ancient Chinese. and its variant combine the "ghost radical" , a pictogram originally showing a figure with an odd face and tail that is used independently as a word for Chinese ghosts and demons, with the character , a pictogram originally showing a cloud and believed to have been pronounced /*[ɢ]ʷə[r]/ or /*ɢun/ in Ancient Chinese. combines the same radical with the character of uncertain origin (possibly a pictogram of an acorn to represent its inner color) but believed to have been pronounced /*bˤrak/ or /*braːɡ/ in Ancient Chinese.

Besides the common meaning of "a soul", was a variant Chinese character for "a lunar phase" and "dregs". The Book of Documents used as a graphic variant for "dark aspect of the moon" – this character usually means "overlord; hegemon". For example, "On the third month, when (the growth phase, ) of the moon began to wane, the duke of Chow [i.e., Duke of Zhou] commenced the foundations, and proceeded to build the new great city of Lǒ". The Zhuangzi "[Writings of] Master Zhuang" wrote (lit. "rotten dregs") "worthless; unwanted; waste matter" with a variant. A wheelwright sees Duke Huan of Qi with books by dead sages and says, "what you are reading there is nothing but the [] chaff and dregs of the men of old!".

In the history of Chinese writing, characters for "lunar brightness" appeared before those for "soul; spirit". The spiritual and "dual souls" are first recorded in Warring States period (475–221 BCE) seal script characters. The lunar or "moon's brightness" appears in both Zhou dynasty (1045–256 BCE) Bronzeware script and oracle bone script, but not in Shang dynasty (ca. 1600–1046 BCE) oracle inscriptions. The earliest form of this "lunar brightness" character was found on a (c. 11th century BCE) Zhou oracle bone inscription.

Etymologies The soul's etymology is better understood than the soul's. Schuessler reconstructs "'spiritual soul' which makes a human personality" and "vegetative or animal soul ... which accounts for growth and physiological functions" as Middle Chinese γuən and pʰak from Old Chinese *wûn and *phrâk.

The (c. 80 CE) gave pseudo-etymologies for and through Chinese character puns. It explains with "deliver; pass on; impart; spread" and "rue (used to keep insects out of books); to weed", and with " compel; force; coerce; urgent" and "white; bright".

What do the words and [] mean? expresses the idea of continuous propagation ([] ), unresting flight; it is the of the Lesser Yang, working in man in an external direction, and it governs the nature (or the instincts, [] ). [] expresses the idea of a continuous pressing urge ([] ) on man; it is the [] of the Lesser Yin, and works in him, governing the emotions ([] ). is connected with the idea of weeding ([] ), for with the instincts the evil weeds (in man's nature) are removed. [] is connected with the idea of brightening ([] ), for with the emotions the interior (of the personality) is governed.Tr. .

Etymologically, Schuessler says "animal soul" "is the same word as" "a lunar phase". He cites the (534 BCE, see below) using the lunar to mean "With the first development of a fetus grows the vegetative soul". , the soul responsible for growth, is the same as the waxing and waning of the moon". The meaning 'soul' has probably been transferred from the moon since men must have been aware of lunar phases long before they had developed theories on the soul. This is supported by the etymology 'bright', and by the inverted word order which can only have originated with meteorological expressions ... The association with the moon explains perhaps why the soul is classified as Yin ... in spite of the etymology 'bright' (which should be Yang), hun's Yang classification may be due to the association with clouds and by extension sky, even though the word invokes 'dark'. 'Soul' and 'moon' are related in other cultures, by cognation or convergence, as in Tibeto-Burman and Proto-Lolo–Burmese *s/ʼ-la "moon; soul; spirit", Written Tibetan cognates bla "soul" and zla "moon", and Proto-Miao–Yao *bla "spirit; soul; moon".

Lunar associations of are evident in the Classical Chinese terms "the moon" (with "toad; toad in the moon; moon") and "moon; moonlight" (with "white; bright; luminous").

The semantics of "white soul" probably originated with "lunar whiteness". Zhou bronze inscriptions commonly recorded lunar phases with the terms "after the brightness has grown" and "after the brightness has died", which Schuessler explains as "second quarter of the lunar month" and "last quarter of the lunar month". Chinese scholars have variously interpreted these two terms as lunar quarters or fixed days, and Wang Guowei's lunar-quarter analysis the most likely. Thus, is from the 7th/8th to the 14th/15th days of the lunar month and is from the 23rd/24th to the end of the month. Yü translates them as "after the birth of the crescent" and "after the death of the crescent". Etymologically, lunar and spiritual < pʰak < *phrâk are cognate with < bɐk < *brâk "white". According to Hu Shih, etymologically means "white, whiteness, and bright light"; "The ancient Chinese civilisations seemed to have regarded the changing phases of the moon as periodic birth and death of its [], its 'white light' or soul." Yü says this ancient association between the soul and the "growing light of the new moon is of tremendous importance to our understanding of certain myths related to the seventh day of the months." Two celebrated examples in Chinese mythology are Xi Wangmu and Emperor Wu meeting on the seventh day of the first lunar month and The Princess and the Cowherd or Qixi Festival held on the seventh day of the seventh lunar month.

The etymology of < γuən < *wûn is comparatively less certain. Hu said, "The word is etymologically the same as the word , meaning "clouds." The clouds float about and seem more free and more active than the cold, white-lighted portion of the growing and waning moon." Schuessler cites two possibilities. Since is the 'bright' soul, is the 'dark' soul and therefore cognate to 'cloud', perhaps in the sense of 'shadowy' because some believe that the soul will live after death in a world of shadows.

The 'clouds' along with the moon make up the singular night canvas to show how the parts of the soul are interdependent. The clouds cover the moon, showing how the hun covers and restrains the po and prevent the release of the "animal soul" or Instinct.

Semantics The correlative "soul" words and have several meanings in Chinese plus many translations and explanations in English. The table below shows translation equivalents from some major Chinese-English dictionaries.

+ Chinese-English dictionary translations of and Dictionary Giles The soul, that part of the soul (as opp. to ) which goes to heaven and is able to leave the body, carrying with it an appearance of physical form; the subliminal self, expl. as . The mind; wits; faculties. The soul; that part of the soul (as opposed to ) which is indissolubly attached to the body, and goes down to earth with it at death; the supraliminal self, expl. as . Form; shape. The disc or substance of the moon from the time it begins to wane to new moon. Mathews The soul, the spiritual part of man that ascends to heaven, as contrasted with . The wits; the spiritual faculties. The animal or inferior soul; the animal or sentient life which inheres in the body – the body in this sense; the animals spirits; this soul goes to the earth with the body. Chao and Yang the soul (of a living person or of the dead) the physical side of the soul Karlgren spiritual soul (as opp. to ) the animal soul of man (as opp. to ) Lin Soul; the finer spirits of man as dist. , the baser spirits or animal forces (Taoism) the baser animal spirits of man, contrasted with finer elements three finer spirits and seven animal spirits), the two together conceived as animating the human body Liang a soul; a spirit. 1. (Taoism) vigor; animation; life. 2. form; shape; body. 3. the dark part of the moon. Wu ① soul ② mood; spirit ③ the lofty spirit of a nation ① soul ② vigour; spirit Ling et al. ① same as ... soul; believed by the superstitious to be an immaterial spiritual entity distinguished from but coexistent with the physical body of a person and a dominant spiritual force, and which leaves upon the person's death. ② spirit; mood. ③ lofty spirit. ① soul; spiritual matter believed by religious people as dependent on human's body. ② vigour; spirit. DeFrancis soul, spirit; mood ① soul; ② vigor; spirit

Both Chinese and are translatable as English "soul" or "spirit", and both are basic components in "soul" compounds. In the following examples, all Chinese-English translation equivalents are from DeFrancis.

"soul; psyche" "soul; spirit" "(colloquial) soul; ghost" "soul; spirit; apparition" "soul; three finer spirits and several baser instincts that motivate a human being" "soul"

and are the most frequently used among these "soul" words.

Joseph Needham and Lu Gwei-djen, eminent historians of science and technology in China, define and in modern terms. "Peering as far as one can into these ancient psycho-physiological ideas, one gains the impression that the distinction was something like that between what we would call motor and sensory activity on the one hand, and also voluntary as against vegetative processes on the other."

Farzeen Baldrian-Hussein cautions about and translations: "Although the term "souls" is often used to refer to them, they are better seen as two types of vital entities, the source of life in every individual. The is Yang, luminous, and volatile, while the is Yin, somber, and heavy."

History Origin of terms Based on usages of and in four historical contexts, Yü extrapolates that was the original name for a human soul, and the dualistic conception of and "began to gain currency in the middle of the sixth century" BCE.

Two earlier 6th century contexts used the soul alone. Both describe "heaven; god" "seizing; taking away" a person's , which resulted in a loss of mental faculties. In 593 BCE (Duke Xuan 15th year), after Zhao Tong behaved inappropriately at the Zhou court, an observer predicted: "In less than ten years [Zhao Tong] will be sure to meet with great calamity. Heaven has taken his [] wits away from him." In 543 BCE (Duke Xiang 29th year), Boyou from the state of Zheng acted irrationally, which an official interpreted as: "Heaven is destroying [Boyou], and has taken away his [] reason." Boyou's political enemies subsequently arranged to take away his hereditary position and assassinate him.