The four pillars is an English translation of the Chinese dynastic phrase “Shēng Chén Bā Zì”. The Chinese term (生辰八字, ShēngChén BāZì) translates to “The Eight Characters of Birth Time”. This is also referred to by the Chinese term (四柱命理學, Sì Zhù MìngLǐ Xué) which translates to Study of “Four Pillars of Life” Principles.
Commonly referred to by the shortened terms, “Four Pillars” or “BāZì”, one of the most frequently used alternate phrase is “Four Pillars of your birth time”. It is called BāZì (八字), Eight Characters, because each of the four pillars (representing the year, month, day, and hour of one’s birth respectively) is represented by two characters; one character for a Heavenly Stem and one character for an Earthly Branch. There are 10 Heavenly Stems (天干; TiānGān) and 12 Earthly Branches (地支; DìZhī). The 12 zodiac animal reference is a folkloric representation of the 12 Earthly Branches.
|The Twelve Earthly Branches|
Year Pillar – Ten Heavenly Stems and Twelve Earthly branches combines and create a sexagenary cycle (See this chart to find the year pillar. If your birth year is not in the 60-year circle, it can be calculated by extrapolation from the figures.) Here is a quick way to convert a year in western calendar into the one represented by stem and branch.
Year’s Heavenly Stem – Last number of a year will indicate the year’s stem
Year’s Earthly Branch – the reminder (1-11) of the year divided by 12 will indicate the year’s branch
Take the year 1985 for example. Last number 5 refers to Yi. 1985 divided by 12 equals an integer 165 with a reminder of 5. Number 5 refers to Chou. So 1985 is Yi Chou year.
Month Pillar – Month pillar has fixed early branches, lunar January to October represented by Yin, Mao, Chen, Si, Wu, Wei, Shen, You, Xu, Hai, Zi and Chou. The heavenly stem is changing according to the year pillar. In fact, the division of two month branches is usually up to the 24 solar terms. From the Beginning of Spring which regarded as the real start of a year, the branch shifts every two solar terms. The representation by lunar months is only an only an approximation.
Earthly Branches and 12 Months
Day Pillar – The recondition to know a day’s stem and branch, one should remember the stem and branch of the first day of that year in Chinese lunar calendar. Then, Chinese calendar has bigger and lesser month, respectively having 30 or 29 days. One stem-branch cycle needs 60 days. If the stem and branch of the first day of that lunar month has been known, there is a way to extrapolate any day within the month, by the different extrapolation rules applied to bigger and lesser months.
Hour Pillar – Similarly, the heavenly branches of the hour pillar is fixed. Jia hour refers to 23:00-01:00, and so forth. The heavenly stem of each day is up to the stem and branch of the day pillar.
Earthly Branches of 24 Hours (12 Shi Chen)