Every reading in Da Liu Ren (大六壬 dà liù rén) begins with two rings of characters, one inside the other. The outer, fixed ring is the Earth Plate; the inner, turning ring is the Heaven Plate. Together they form the da liu ren heaven earth plate (天地盘 tiān dì pán), and the whole board depends on a single decision: how far to rotate the inner ring against the outer one. Get that alignment right and everything else — the generals, the lessons, the transmissions — falls into place mechanically. This article explains the two plates and the one move that fixes them.
The Earth Plate: twelve branches that never move
The Earth Plate (地盘 dì pán) is the ground the board stands on. It holds the twelve Earthly Branches — 子丑寅卯辰巳午未申酉戌亥 (zǐ chǒu yín mǎo chén sì wǔ wèi shēn yǒu xū hài) — arranged in their standard ring positions and left there. It does not rotate, it does not change from question to question, and it is the same for every casting. Zi sits where Zi always sits; Wu sits opposite it; the ring reads in fixed order all the way around.
If you have met these twelve branches in Ba Zi (八字 bāzì), they are the same characters you already know from the heavenly stems and earthly branches that build a birth chart. The difference is what they are doing here. In Ba Zi the branches are pillars of a life. On the Earth Plate they are simply fixed reference points — twelve labelled seats around a circle, waiting for the upper ring to land on them.
八字 · Four Pillars
Start with your own chart. Plot your Ba Zi free — exact solar-term accuracy, in your browser. The birth chart is where every reading begins.
>The Heaven Plate: the same twelve branches, but turning
The Heaven Plate (天盘 tiān pán) carries the identical twelve branches, in the same order, on a ring that sits above the Earth Plate and can be rotated. Because both rings hold the same sequence, rotating the Heaven Plate simply slides each branch to sit over a different Earth-Plate branch. Once the ring is turned to its correct position and locked, you can read straight down: above every fixed Earth-Plate branch stands one Heaven-Plate branch.
That vertical pairing — what sits above what — is the raw material for everything that follows. The Twelve Heavenly Generals (十二天将 shí’èr tiān jiàng) ride on the Heaven Plate branches, and the Four Lessons (四课 sì kè) are read by taking a branch on the Earth Plate and noting the branch standing above it. So the only real question the plates pose is: at what angle should the Heaven Plate be set. Everything downstream is determined once that angle is chosen.
The one alignment: Monthly General over the hour
Here is the move that fixes the board. The Heaven Plate is rotated so that the Monthly General (月将 yuè jiàng) sits directly over the hour branch of the question (占时 zhàn shí). That single alignment sets the whole plate. Once the Monthly General is placed over the hour, every other Heaven-Plate branch is thereby fixed over its Earth-Plate partner, and no further choice remains.
The Monthly General is the Sun’s position among the twelve branches, read by solar term (太阳过宫 tài yáng guò gōng) rather than by calendar month. It advances one palace roughly every solar-term pair. The mapping runs, for example, from 亥 (登明 Dēng Míng) after 雨水 (yǔ shuǐ), to 戌 (河魁 Hé Kuí) after 春分 (chūn fēn), and onward around the ring; the full table and its solar-term boundaries are set out in the Monthly General and the Sun’s position. The practical point for the plates is only this: the Monthly General gives you the branch, the hour of the question gives you the seat, and you turn the Heaven Plate until the first lands on the second.
Two inputs, then, decide the entire da liu ren heaven earth plate — the Monthly General (fixed by the date’s solar term) and the hour branch (fixed by when the question is asked). Change the hour and the Heaven Plate rotates to a new angle; change the season enough to shift the Monthly General and it rotates again. The Earth Plate stays put through all of it.
Why one alignment can fix everything
It looks almost too simple that a single rotation should determine a whole reading, so it is worth being clear about why. Because both rings carry the same twelve branches in the same order, fixing one pairing fixes all twelve at once — the rings move as rigid wheels, not as loose beads. The alignment is not one fact among many; it is the one degree of freedom the system has. Lock it, and the board is closed.
From there the derivation is mechanical and deterministic. The Heaven Plate positions place the Twelve Heavenly Generals; the day’s stem and branch, read against the finished plate, yield the Four Lessons; and the Nine Methods (九宗法 jiǔ zōng fǎ) work the lessons into the Three Transmissions (三传 sān chuán). None of that involves a second free choice. This is why practitioners treat the plate build as arithmetic, not interpretation: the reading — the part where judgement lives — comes later, once the board is standing. For the orientation of where this sits in the wider art, see what Da Liu Ren is.
A note on honesty about the tables. The solar-term-to-Monthly-General mapping should be checked against a current, classical reference before it drives any real casting; boundaries are solar terms, and traditions differ on edge cases at those boundaries. The structure above — fixed Earth Plate, rotating Heaven Plate, Monthly General over the hour — is stable across schools. It is the underlying grammar of the board.
The plates are Chinese metaphysics at its most geometric, but the same twelve branches sit at the root of your own birth chart. If you want to see them working in the destiny system first, plot your Four Pillars free with the Ba Zi calculator and read the branches in context — the same alphabet, put to a different question.
