Heavenly Stems
The ten Heavenly Stems or Celestial Stems () 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. Table. The Japanese names of the Heavenly Stems are based on their corresponding Wu Xing elements (e.g. "ki" for "wood", "mizu" for "water"), followed by the possessive/attributive particle の ("no") and the word え ("e", "older sibling") or the word と ("to", "younger sibling", originally おと "oto"). The Manchu names are based on their respective elements' colors. Origin. 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. Jonathan Smith has proposed that the heavenly  stems predate the Shang and originally referred to ten asterisms along the ecliptic, of which their oracle bone script characters were drawings; he identifies similarities between these and asterisms in the later Four Images and Twenty-Eight Mansions systems. These would have been used to track the moon's progression along its monthly circuit, in conjunction with the earthly branches referring to its phase. 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. Current usage. The Stems  are still commonly used nowadays in East Asian counting systems similar to the way the alphabet is used in English. For example: