Geng Wu Pillar (庚午) — Yang Metal over Horse
What the Geng Wu pillar (庚午) is in BaZi: yang Metal on the Horse branch, its hidden stems, its nayin Earth by the Roadside, and when it returns.
What is the Geng Wu pillar?
Geng Wu is the pair 庚午: the Geng stem standing over the Wu branch. It is number 7 of the sixty possible combinations. The same pair can appear as a year pillar, a month pillar, a day pillar or an hour pillar, and which one it is changes how it is read — a year pillar is read as the environment someone was born into, a day pillar as the person themselves.
What the two characters are
庚 Geng — The blade. Geng people are decisive, principled and cut straight through noise.
午 Wu — the Horse, a Fire branch covering 11:00 – 13:00. As a branch it is the third of the four layers a chart is read through: the animal name people know is only this one character, with no stem attached.
Geng Wu is the classic tension pillar of the opening twelve. Yang Metal on Wu is metal placed in fire: the branch's Fire offends the stem even while the Earth hidden below it partly rescues it. Classical readings describe this arrangement as being shaped by resistance, which is exactly what the chart has to be read for.
How the two meet
Inside a pillar the stem and the branch are not equal partners. The convention is to read them as a relationship: one of them is doing something to the other. Here, the branch controls the stem.
The branch constrains the stem. The pillar reads as pressure applied at the base rather than at the top — the stem is exposed to something it cannot simply override. This is the arrangement practitioners look at first when a chart is described as under strain, and how much it matters depends on how strong the stem already is.
The stem has no root in this branch. Nothing hidden below it is made of the same element, so the stem is running on support from elsewhere in the chart or on nothing at all.
What is hidden in the branch
A branch is not one element. Each of the twelve carries up to three stems inside it — the main qi that gives it its name, and one or two lesser ones. Those hidden stems are where most of the actual weight in a chart comes from, and they are read even though nothing of them appears in the four visible characters.
| Hidden stem | Element | Role in the branch |
|---|---|---|
| 丁 Ding | 火 Fire · Yin | main qi — the element the branch is named for |
| 己 Ji | 土 Earth · Yin | middle qi |
When a practitioner says a pillar is strong or weak, this table is usually the reason — a stem with a hidden ally below it behaves nothing like the same stem sitting on an empty branch.
Where this pillar sits in the sixty
庚午 is number 7 of the sixty combinations. Its nayin — the classical image assigned to it — is 路旁土 Earth by the Roadside, a Earth image. The Earth images describe a location rather than a thing: the roadside, the city wall, the rooftop, the highway. Each is defined by what it holds up.
As a day pillar, this pair comes round every sixty days. The next six:
As a year pillar, the pair returns only once every sixty years — these are the recent and coming ones:
The day dates are calculated from the same engine that runs the chart calculator. Note that the Chinese day starts at 23:00: a birth late in the evening belongs to the next day pillar, which shifts the whole calculation by one.
Reading a pillar on its own
A single pillar is not a reading. What this page describes is the internal structure of 庚午 — which element is on top, what is underneath it, and whether the support is there. To turn that into something about a person you need the other three pillars and a day master to read them against, because the ten gods that carry the actual meaning are relationships to the day master rather than properties of a pillar.
The other pillars in this set
Common questions
See your four pillars
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