地支
twelve earthly branches — the hidden layer
The twelve branches — 子丑寅卯辰巳午未申酉戌亥 — are the working layer of the chart. Each one is a bundle of jobs: it marks a two-hour period of the day (the 时辰), a month of the solar year, a direction, a season, and — as a mnemonic — a zodiac animal. And each branch hides one to three stems inside it, the 藏干 hidden stems, which is why the branch layer is called "hidden."
The branches are read two ways at once: as the branch itself (its phase and polarity) and as the stems it hides. This is the difference between the visible and the concealed — what a moment shows, and what it carries underneath.
the twelve branches in full
Read the table as four seasons folded across twelve seats: 寅卯辰 spring (wood, then earth storing wood), 巳午未 summer (fire, then earth storing fire), 申酉戌 autumn (metal, then earth storing metal), 亥子丑 winter (water, then earth storing water). The four 土 branches — 辰戌丑未 — are the season's storehouses: each one vaults the phase that just finished.
| branch | phase · polarity · animal · season · hour · hidden stems 藏干 |
|---|---|
| 子 zǐ | 水 · yang · rat · winter · 23:00–00:59 · hides 癸 |
| 丑 chǒu | 土 · yin · ox · winter's turning · 01:00–02:59 · hides 己 癸 辛 |
| 寅 yín | 木 · yang · tiger · spring begins · 03:00–04:59 · hides 甲 丙 戊 |
| 卯 mǎo | 木 · yin · rabbit · spring in leaf · 05:00–06:59 · hides 乙 |
| 辰 chén | 土 · yang · dragon · wet earth · 07:00–08:59 · hides 戊 乙 癸 |
| 巳 sì | 火 · yin · snake · fire coiled · 09:00–10:59 · hides 丙 庚 戊 |
| 午 wǔ | 火 · yang · horse · noon · 11:00–12:59 · hides 丁 己 |
| 未 wèi | 土 · yin · goat · late summer · 13:00–14:59 · hides 己 丁 乙 |
| 申 shēn | 金 · yang · monkey · autumn forms · 15:00–16:59 · hides 庚 壬 戊 |
| 酉 yǒu | 金 · yin · rooster · pure metal · 17:00–18:59 · hides 辛 |
| 戌 xū | 土 · yang · dog · dry mountain · 19:00–20:59 · hides 戊 辛 丁 |
| 亥 hài | 水 · yin · pig · deep water · 21:00–22:59 · hides 壬 甲 |
hidden stems — the storehouse doctrine — 藏干
Why do branches hide stems? Because a season is not a single thing — it is the arrival, the height, and the departure of its phase. The tradition names the three seats: 主气 zhǔ qì the presiding stem (the season's own phase), 中气 zhōng qì the middle stem (what is arriving or leaving), and 余气 yú qì the remnant stem (what the season just finished). 寅, the first month of spring, hides 甲 (wood — presiding), 丙 (fire — arriving), 戊 (earth — the ground everything stands on): three layers in one branch.
Most branches hide fewer: the pure four (子卯午酉) hide only one stem each — they sit at the season's exact center, where nothing else is present. The storehouse four (辰戌丑未) hide three, and the four in-between (寅申巳亥) hide three as well, with their main stem leading. The app shows the hidden stems of every pillar in the chart grid's 藏干 layer, each tagged with its 十神 (module 7).
the twelve hours — 时辰 — 时辰
The day divides into twelve two-hour periods, and each has a branch. 子时 begins at 23:00 — the day starts at night, at the moment the new thing is first conceived, not at dawn. The hour branch of a birth is the fourth pillar of the chart, and its hidden stems matter as much as the branch itself. (A traditional complication, 晚子时 "late 子 hour," treats the last hour before midnight as belonging to the next day — the app's 起运 computation follows the lunar_python convention of counting 23:xx as the day's final 时辰.)
the zodiac animals
The twelve animals — rat, ox, tiger, rabbit, dragon, snake, horse, goat, monkey, rooster, dog, pig — are mnemonics for the branches, a folk memory system for a calendar. That is all they are. The animal is a label on the branch, not a personality test: a "dragon" year tells you the year's branch was 辰, nothing more. Anyone who tells you what a person is like "because they are a rabbit" has confused the mnemonic with the math.