Yin Wood Snake (Yi Si, 乙巳) day pillar
A Yin Wood day master, the Vine, sitting on the Snake.
Your day pillar is the pair of characters for the day you were born. The top one, the stem, is your day master — you. The bottom one, the branch, is what it sits on. The sixty pillars come round in turn, one a day, so about one person in sixty was born on a Yi Si day.
Its sound element: Lamp Fire (Fu Deng Huo, 覆灯火)
The sixty pillars go in pairs, and each pair carries a sound element (Na Yin, 纳音) — an image, separate from the element of the stem. The classic San Ming Tong Hui (三命通会) describes each pillar by it:
Lamplight; likes what the lamp before it likes, and above all the Monkey and Rooster, and autumn.
灯光也，同上，尤喜申酉及秋
What the Snake holds, and what it is to Yin Wood
Each branch holds one to three stems. The ones under your own day master are the closest things to you in the chart.
- Yang Fire (Bing, 丙), the main one — Hurting Officer (Shang Guan, 伤官). What you produce, opposite polarity. Output with an edge on it. The name means it injures the Direct Officer (正官), which is why the tradition reads it as talent that does not sit well with authority.
- Yang Metal (Geng, 庚) — Direct Officer (Zheng Guan, 正官). What controls you, opposite polarity. Authority in its orderly form: office, rule, the structure you fit into.
- Yang Earth (Wu, 戊) — Direct Wealth (Zheng Cai, 正财). What you control, opposite polarity. Wealth held steadily — earned, kept, accounted for.
A Yi Si day at each birth hour: San Ming Tong Hui (三命通会)
Two volumes of this classic go hour by hour, and at each hour say something about this exact day pillar. These are its sentences on a Yi Si day; what it says about the other five Yin Wood days is on the Yin Wood day master page. Hours are true solar time, not clock time.
Rat hour 23:00–01:00 · Yang Fire Rat (Bing Zi, 丙子)
favourable. If Snake (巳) or Horse (午) stand in year or month, the life is short; otherwise the self is solitary and toils. Pure Earth, wealth strong producing the officer, running a western period; Rat (子) and Dragon (辰) running Water and Fire periods — both second or third grade. A Monkey (申) month is Direct Officer (正官), a Rooster (酉) month Seven Killings (偏官), a Rabbit (卯) month the Established Prosperity (建禄) — all favourable. It dislikes a Wood Tiger (甲寅) month, punishment and early death; a Wood Rooster (乙酉) month is low and base.
吉。若巳午年月，寿促，不然，身孤劳碌，纯土，财旺生官，行西运；子辰，行水火运，俱二三品贵。申月正官，酉月偏官，卯月建禄，俱吉。忌甲寅月，刑夭。乙酉月下贱。
Ox hour 01:00–03:00 · Yin Fire Ox (Ding Chou, 丁丑)
Pig (亥), Rabbit (卯), Goat (未) and Tiger (寅) months, noble. Where a month of Metal qi gives it something to lean on, the blessing is weighty.
生，亥卯未寅月，贵。通金气月有倚托者，福重。
Tiger hour 03:00–05:00 · Yang Earth Tiger (Wu Yin, 戊寅)
solitary, harmed, ordinary. If Monkey (申) or Yang Metal (庚) stand in year or month it is Direct Officer (正官); Ox (丑) or Yin Metal (辛), the Seven Killings (七煞) — both noble. A Dragon (辰) month running a northern period, favourable.
孤克平常。若年月申庚，正官；丑辛，七煞，俱贵。辰月，北方运，吉。
Rabbit hour 05:00–07:00 · Yin Earth Rabbit (Ji Mao, 己卯)
spring solitary and poor, summer middling, autumn carrying illness, winter noble. Horse (午) and Dragon (辰) in year or month, and the branches linked in one run, better still.
春孤贫，夏平，秋带疾，冬贵。午辰年月、地支一路相连，尤吉。
Dragon hour 07:00–09:00 · Yang Metal Dragon (Geng Chen, 庚辰)
dealings made and unmade; a monk or priest, wealth and rank with illness. A common man is punished and harmed in wife and children. Monkey (申), Rat (子), Dragon (辰), Rabbit (卯) and Snake (巳) in year or month, noble.
作事成败，僧道富贵带疾。常人刑克妻子。申子辰卯巳年月，贵。
Snake hour 09:00–11:00 · Yin Metal Snake (Xin Si, 辛巳)
harms the wife, and wife and children both come late. If in Snake (巳), Rooster (酉) or Ox (丑) months, the Wood soft and the Metal heavy, it governs carrying illness; otherwise the life is short. Yang Wood (甲), Snake, Rat (子) and Snake in year or month enter the Seven Killings (偏官) pattern, and a western period gives the censorate. A spring month with the self strong is better still.
克妻，妻子俱晚。若巳酉丑月，木柔金重，主带疾。不然寿促。甲巳子巳年月，入偏官格，西运，风宪。春月身旺，更吉。
Horse hour 11:00–13:00 · Yang Water Horse (Ren Wu, 壬午)
favourable. Spring and summer, wealth and rank. Autumn and winter, ordinary.
吉，春夏富贵。秋冬平常。
Goat hour 13:00–15:00 · Yin Water Goat (Gui Wei, 癸未)
if not noble then wealthy, hard first and easy after. Pure Horse (午), third grade. Dragon (辰), Dog (戌) and Ox (丑) months, all favourable.
不贵则富，先难后易。纯午、三品贵。辰戌丑月，俱吉。
Monkey hour 15:00–17:00 · Yang Wood Monkey (Jia Shen, 甲申)
the self strong and the officer strong. Spring, clever and conspicuous, office to the fourth grade. Summer, body and mind toil. Autumn and winter, eye complaints. A Horse (午) year or month running a wealth period, noble.
身强官旺。春，聪明显达，官至四品。夏，身心劳碌。秋冬眼疾。午年月，行财运，贵。
Rooster hour 17:00–19:00 · Yin Wood Rooster (Yi You, 乙酉)
spring favourable. Summer, Hurting Officer (伤官) held in check, good. Autumn, the Wood weak and the Metal heavy — early death, or else illness. Winter, the blessing thick but still an early death.
春吉。夏，伤官有制，好。秋，木弱金重，夭，不然有疾。冬，福厚亦夭。
Dog hour 19:00–21:00 · Yang Fire Dog (Bing Xu, 丙戌)
favourable. Ox (丑), Dog (戌) and Goat (未) in year or month, the censorate and the six ministers. A Pig (亥) month running an eastern period, the academy, pure and noble.
吉。丑戌未年月，风宪六卿。亥月，行东运，翰院清贵。
Named days in Yuan Hai Zi Ping (渊海子平)
These are decided by the day pillar alone, so everyone born on a Yi Si day is in them. The work attaches conditions to most of them; the passage is given whole.
The ten unpardonable days
The day pillar is one of the ten whose prosperity star (禄) falls in its own decade's Void (空亡). The passage is explicit that it is not simply bad — 况犯者未必皆凶，若内有吉神相扶，贵气相辅，当为吉论 — so it is reported and not graded.
六甲旬中十个日值禄人空亡，如甲辰、乙巳，甲以寅为禄，乙以卯为禄，甲辰旬以寅卯为空亡……余如丙申、丁亥、庚辰、戊戌、癸亥、辛巳、乙丑等日皆仿此。命中犯者，当以日上见之为是，其余不论
The Snake and the other animals
When the day branch meets these — in a year, a ten-year luck period, or someone else’s chart — the classics read it by these relationships.
- Clashes with
- Pig
- Pairs with (six harmony)
- Monkey
- In a trine with
- Ox, Rooster
- Punishment with
- Tiger, Monkey
- Harms
- Tiger
- Breaks
- Monkey
The next Yi Si days: 27 November 2026, 26 January 2027, 27 March 2027. It returns every sixty days.
Famous people born on a Yi Si day
- Yuan T. Lee Chemist · Nobel Prize in Chemistry, 1986
The Yin Wood day master · Before it: Jia Chen · After it: Bing Wu · All sixty day pillars