The ten Heavenly Stems or Celestial Stems (Chinese: 天干; pinyin: tiāngān) are a Chinese system of ordinals that first appear during the Shang dynasty, c. 1250 BC, as the names of the ten days of the week. They were also used in Shang-period ritual as names for dead family members, who were offered sacrifices on the corresponding day of the Shang week. The Heavenly Stems were used in combination with the Earthly Branches, a similar cycle of twelve days, to produce a compound cycle of sixty days. Subsequently, the Heavenly Stems lost their original function as names for days of the week and dead kin, and acquired many other uses, the most prominent and long lasting of which was their use together with the Earthly Branches as a 60-year calendrical cycle. The system is used throughout East Asia.
The Japanese names of the Heavenly Stems are based on their corresponding Wu Xing elements, while their Manchu names are based on their respective elements' colors.
The Shang people believed that there were ten suns, each of which appeared in order in a ten-day cycle (旬; xún). The Heavenly Stems (tiāngān 天干) were the names of the ten suns, which may have designated world ages as did the Five Suns and the Six Ages of the World of Saint Augustine. They were found in the given names of the kings of the Shang in their Temple Names. These consisted of a relational term (Father, Mother, Grandfather, Grandmother) to which was added one of the ten gān names (e.g. Grandfather Jia). These names are often found on Shang bronzes designating whom the bronze was honoring (and on which day of the week their rites would have been performed, that day matching the day designated by their name). David Keightley, a leading scholar of ancient China and its bronzes, believes that the gān names were chosen posthumously through divination. Some historians think the ruling class of the Shang had ten clans, but it is not clear whether their society reflected the myth or vice versa. The associations with Yin-Yang and the Five Elements developed later, after the collapse of the Shang Dynasty.
The literal meanings of the characters were, and are now, roughly as follows. Among the modern meanings, those deriving from the characters' position in the sequence of Heavenly Stems are in italics.
first (book I, person A etc.), methyl group, helmet, armor, words related to beetles, crustaceans, fingernails, toenails
second (book II, person B etc.), ethyl group, twist
The Stems are still commonly used nowadays in East Asian counting systems similar to the way the alphabet is used in English. For example:
Korea and Japan also use heavenly stems on legal documents in this way. In Korea, letters gap (甲) and eul (乙) are consistently used to denote the larger and the smaller contractor (respectively) in a legal contract, and are sometimes used as synonyms for such; this usage is also common in the Korean IT industry. The 11th to 22nd letters (k to v) are represented by the terrestrial branches, and the final four letters (w to z) are represented by '物', '天', '地', and '人', respectively. In case of upper-case letters, the radical of '口' (the 'mouth' radical) may be added to the corresponding celestial stem, terrestrial branch, or any of '物', '天', '地', and '人' to denote an upper-case letter.
Vitamins (although currently, in this case, the ABC system is more popular)
Characters conversing in a short text (甲 speaks first, 乙 answers)
Students' grades in Taiwan: with an additional Yōu (優 "Excellence") before the first Heavenly Stem Jiǎ. Hence, American grades A, B, C, D and F correspond to 優, 甲, 乙, 丙 and 丁 (yōu, jiǎ, yǐ, bǐng, dīng).
^David N. Keightley, "The Quest for Eternity in Ancient China: The Dead, Their Gifts, Their Names" in Ancient Mortuary Traditions of China ed. by George Kuwayama. Los Angeles County Museum of Art, 1987, pp. 12–24.
^William McNaughton. Reading and Writing Chinese. Tokyo: Charles E. Tuttle, 1979.
^Wenlin Dictionary: 己 may have depicted thread on a loom; an ancient meaning was 'unravel threads', which was later written 紀 jì. 己 was borrowed both for the word jǐ 'self', and for the name of the sixth Heavenly Stem (天干).
^Wenlin Dictionary: "The seal has 𢆉 'knock against, offend' below, and 亠 above; the scholastic commentators say: to offend (亠 = ) 上 the superiors"
^Wenlin Dictionary: 壬 rén depicts "a 丨 carrying pole supported 一 in the middle part and having one object attached at each end, as always done in China" —Karlgren (1923). (See 扁担 biǎndan). Now the character 任 rèn has the meaning of carrying a burden, and the original character 壬 is used only for the ninth of the ten heavenly stems (天干).
^Wenlin Dictionary: 癶 "stretch out the legs" + 天; The nicely disposed grass, on which the Ancients poured the libations offered to the Manes
Barnard, Noel (1986). "A new approach to the study of clan-sign inscriptions of Shang". In Kwang-chih Chang (ed.). Studies of Shang archaeology : selected papers from the International Conference on Shang Civilization. New Haven: Yale University Press. pp. 141–206. ISBN978-0-300-03578-0.
Chang Tai-Ping (1978). "The role of the t'ien-kan ti-chih terms in the naming system of the Yin". Early China. 4: 45–48.
Keightley, David (2000). The ancestral landscape: time, space, and community in late Shang China, ca. 1200-1045 B.C. Berkeley: University of California, Berkeley, Center for Chinese Studies. ISBN978-1-55729-070-0.
Norman, Jerry (1985). "A note on the origins of the Chinese duodenary cycle". In Graham Thurgood (ed.). Linguistics of the Sino-Tibetan area : the state of the art : papers presented to Paul K. Benedict for his 7lst birthday. Canberra: Australian National University. pp. 85–89.
Pulleyblank, E. G. (1995). "The ganzhi as phonograms". Early China News. 8: 29–30.