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BaZi (Four Pillars of Destiny) · Day Master 10 of 10

Guǐ 癸, yin Water: the weakest water, which reaches the Milky Way

Guǐ 癸 is the tenth and last Heavenly Stem, yin Water, and the day master of any BaZi chart whose day stem it is. The classical images make it rain and dew in heaven and springs on earth, spring rain in the sky. The 滴天髓 calls it the weakest of the ten, and in the same line the one that reaches the Milky Way. As a day master it is rooted in 子, 丑 and 辰.

The ten Heavenly Stems in a row from 甲 to 癸, paired by phase, with 癸 Guǐ marked; below, the five phases on a circle, with arrows for the producing order and lines for the overcoming order, showing that Metal produces Water, Water produces Wood, Water overcomes Fire and Earth overcomes Water. Wood 甲 Jiǎ 乙 Yǐ Fire 丙 Bǐng 丁 Dīng Earth 戊 Wù 己 Jǐ Metal 庚 Gēng 辛 Xīn Water 壬 Rén 癸 Guǐ 木 Wood 火 Fire 土 Earth 金 Metal 水 Water Guǐ · Water Produced by Metal Produces Wood Overcomes Fire Overcome by Earth produces overcomes
癸 among the ten stems, and Water in the two classical orders: produced by Metal, producing Wood, overcoming Fire, overcome by Earth.

Facts

Order
10 of 10, the tenth Heavenly Stem
Character
癸 Guǐ
Phase and polarity
Water 水, yin 陰
Season of its phase
Winter
Produced by; produces
Metal; Wood
Overcomes; overcome by
Fire; Earth
Rooted in (hidden in)
子 Zǐ (main qi), 丑 Chǒu (residual qi), 辰 Chén (middle qi)
Comes into office (祿)
子
Blade (陽刃)
None: in the Ziping rule only the yang stems have one
Born in (長生)
卯, running the stages backward
Combines with
戊 Wù, leaning to Fire
Clashes with
丁 Dīng
Our image
Morning dew (EsoTerrier's modern image)

Meaning

The 滴天髓 gives each stem a verse of eight short lines. For 癸 it reads, in the 輯要 text:

癸水至弱,達於天津,龍德而運,功化斯神,不畏火土,不論庚辛,合戊見火,火根乃真。

In our translation: Guǐ water is the weakest of all, yet it reaches the heavenly ford. Moving with the dragon's virtue, its transforming work is marvellous. It fears neither fire nor earth, and takes no account of 庚 or 辛. Combined with 戊 and meeting fire, it transforms truly only on a true root of fire.

The heavenly ford (天津) is the Milky Way. The commentary reads the verse as water's quiet work wherever there is wood in the chart: growing wood, checking fire, moistening earth and feeding metal, as a dragon moves water. 任鐵樵's edition has 得龍而運, moving when it gains the dragon (辰), and ends 化象斯真, then the transformation is real.

The 三命通會 makes 癸 rain and dew in heaven and springs and veins of water on earth: "living water" (活水), soft, glad to be produced by yin metal, born in 卯 among the flourishing trees and hemmed in by earth and metal in 申. Its sky image is spring rain. The 窮通寶鑑 sees the 癸 of the first month as the essence of rain and dew, softest of all, wanting 辛 as its source and 丙 to warm it, yin and yang in harmony.

Our chart calls 癸 morning dew: intuitive, sensitive, thoughtful and caring, with oversensitivity, and keeping things to yourself, as its cost. Dew is also among the classical images; the one-word version is EsoTerrier's modern simplification, labelled as ours.

In a chart

A 癸 day master has roots wherever 癸 is hidden in a branch: 子 Zǐ (main qi), 丑 Chǒu (residual qi), 辰 Chén (middle qi). Its 祿, the branch where its qi comes into office (臨官), is 子. In the Ziping rule only the yang stems have a blade, though the 三命通會 reports an older rule that gave 癸 one in 丑. It is born (長生) in 卯 and, as a yin stem, runs the twelve stages backward from there, the rule every tool prints and the classics dispute; the stages are phases of its qi.

It combines with 戊 Wù (天干五合), a pair the 三命通會 calls 無情之合 (the heartless match), leaning to Fire; it clashes with 丁 Dīng. Its own phase is strongest in winter.

To a 癸 day master the ten stems are: 甲 Hurting Officer (傷官); 乙 Eating God (食神); 丙 Direct Wealth (正財); 丁 Indirect Wealth (偏財); 戊 Direct Officer (正官); 己 Seven Killings (七殺); 庚 Direct Resource (正印); 辛 Indirect Resource (偏印); 壬 Rob Wealth (劫財); 癸 Friend (比肩). A second 癸 elsewhere in the chart is a Friend; the day stem itself is the Day Master and is not one of the Ten Gods.

What this page leaves out

The classical chapters on 癸 also say, in the idiom of their age, what such a chart means for rank, kin, marriage and fortune. We record that they do and repeat none of it. Nor do we say whether a 癸 day master is strong or weak, or which useful god it needs: the tradition weighs both, and EsoTerrier computes neither.

Correspondences

Each item with how it stands: “sourced” is in the work cited, “our construction” is EsoTerrier’s own, and “disputed” means the sources disagree.

Opening of the 滴天髓 verse
「癸水至弱」 sourced
Sky image, 三命通會
Spring rain (春霖) sourced
In heaven and on earth, 三命通會
In heaven rain and dew, on earth springs and veins of water (在天為雨露,在地為泉脈) sourced
The first month, 窮通寶鑑
In the first month 癸 is the essence of rain and dew, softest of all; it wants 辛 as its source and 丙 to warm it, "yin and yang in harmony" (正月癸水) sourced
Combination, 三命通會
With 戊: 無情之合 (the heartless match) sourced
Nobleman star (天乙貴人)
卯 and 巳; a symbolic star we do not chart yet sourced
Academic star (文昌)
卯; a symbolic star we do not chart yet sourced
Blade under an older rule
丑, a rule the 三命通會 reports and the Ziping method drops disputed
Our image, traits and challenge
Morning dew: intuitive, sensitive, thoughtful and caring; its challenge: oversensitivity, and keeping things to yourself our construction
Morning dew as the classical meaning
A modern image; the classics give the ones above disputed
First meaning of the character
Uncertain; the stems are first attested as day names of the Shang week disputed

How the schools read it

滴天髓, the verse
The weakest water, which reaches the Milky Way and works quietly on every phase. Attributed to 京圖 of the Song or to Liu Bowen; one edition study dates the text mid-Ming or later.
任鐵樵, 滴天髓闡微 (after 1820)
Reads 得龍而運, 不愁火土 and 化象斯真 where the 輯要 has 龍德而運, 不畏火土 and 火根乃真.
三命通會 (Ming)
Rain and dew, springs and veins of water; living water; spring rain.
窮通寶鑑 (Qing)
The softest rain and dew, sourced in 辛 and warmed by 丙.
Modern English teaching
The one-word image, morning dew, a simplification of the classical images.
EsoTerrier
Shows morning dew as its own image, labelled, beside the texts.

Claims about it

  • "Morning dew" is the traditional meaning of 癸.

    disputed

    What the record shows: It is a modern teaching image, and ours on the chart. The 三命通會 has rain, dew, springs and spring rain; the 滴天髓 has the weakest water that reaches the Milky Way.

  • The day stem is itself a Ten God, the Friend (比肩).

    false

    What the record shows: A 癸 in another pillar is a Friend to a 癸 day master; the day stem itself is the reference point, labelled Day Master (日主) by every tool we surveyed.

  • 癸 runs the twelve stages backward, born (長生) in 卯.

    disputed

    What the record shows: The 三命通會 says so and every tool prints it. The 滴天髓's older commentary already questions it, and 任鐵樵 rejects separate yin stages. We print the backward rule and label it.

  • A 癸 day master can be scored strong or weak, and its useful god computed.

    disputed

    What the record shows: The classics ground the useful god in at least four different ways. EsoTerrier computes neither the strength nor the useful god.

  • The classical chapters on 癸 tell a person's rank, marriage and length of life.

    told as lore

    What the record shows: The texts do make such pronouncements, in the idiom of their age. We take only their images and the logic of the phases.

Elsewhere on EsoTerrier

Sources

Primary texts (5)
  1. 淵海子平, the Ming compilation by 楊淙 of 徐大升's Song works. Chinese Wikisource transcription. zh.wikisource.org/wiki/淵海子平
  2. Wan Minying, 三命通會, 12 juan (Ming). Chinese Wikisource transcription. zh.wikisource.org/wiki/三命通會
  3. 滴天髓, the 滴天髓輯要 text with its older commentary. Chinese Wikisource. zh.wikisource.org/wiki/滴天髓
  4. 窮通寶鑑, the Qing edition by 余春台 of the 欄江網. Chinese Wikisource transcription. zh.wikisource.org/wiki/窮通寶鑑
  5. 任鐵樵, 滴天髓闡微 (after 1820), with the 原注. Chinese Wikisource transcription. zh.wikisource.org/wiki/滴天髓闡微
Studies and other sources (3)
  1. Na Hyeok-Jin and Kim Ki-Seung, "A Study on the Editions of Myeongri Original Text Jeokcheonsu (滴天髓)", Industry Promotion Research 6(3) (2021): 49 ff. doi.org/10.21186/IPR.2021.6.3.049
  2. Adam Smith, "The Chinese sexagenary cycle and the ritual foundations of the calendar", in John M. Steele (ed.), Calendars and Years II. Oxford: Oxbow, 2011 (read at abstract level).
  3. "Heavenly Stems", Wikipedia (orientation only). en.wikipedia.org/wiki/Heavenly_Stems
Our own research (4)
  1. EsoTerrier, BaZi and Luck Pillars research: conventions, naming and the tools surveyed, 9 to 13 October 2026.
  2. EsoTerrier, the BaZi data tables with their sources: hidden stems, Ten Gods, Na Yin, twelve stages, void branches, relations and symbolic stars.
  3. EsoTerrier calculation engine, the BaZi and Luck Pillars services and their documentation.
  4. EsoTerrier, the owner's decisions of 13 October 2026 on how the day-master pages show the images.

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By EsoTerrier. Written with AI assistance from our research and checked against its sources; last revised 19 October 2026. How we write these pages.

First published ; last revised . Corrections: support@esoterrier.com.

Chinese quotations are from public-domain texts as transcribed on Chinese Wikisource (CC BY-SA 4.0); the translations and readings are EsoTerrier's own.