# Chinese metaphysics

Four pillars, the calendar, feng shui and date selection. The calendar is derived from the ephemeris rather than from tables: a solar term is the instant the Sun reaches a multiple of 15° of longitude, and a lunar month begins on the Beijing day containing a new moon.

<Aside type="tip" title="What is here that the free libraries do not have">
`lunar-typescript` and `iztro` are MIT and give you the pillars, 藏干, 纳音 and 十神 for nothing, and it is worth saying so plainly. What they do not have: 神煞, branch interactions (刑冲合害), a day-master strength reading, true solar time, a flying-star chart by sitting and facing, the Kua number. Plus 21 languages over all of it.
</Aside>

## Sections

<CardGrid>
  <LinkCard title="BaZi: the four pillars" href="/en/chinese/bazi/" description="Pillars, hidden stems, na yin, the twelve stages, symbolic stars, interactions, day-master strength." />
  <LinkCard title="Zi Wei Dou Shu" href="/en/chinese/ziwei/" description="Star placement, the twelve palaces, the 四化 and four school switches." />
  <LinkCard title="Conventions" href="/en/chinese/conventions/" description="The four axes calculators disagree on, and our answer to each. With a run against an external CC0 dataset." />
  <LinkCard title="Flying stars" href="/en/feng-shui/flying-star/" description="Nine palaces, period, sitting and facing, the year's afflictions." />
  <LinkCard title="Tong Shu (date selection)" href="/en/feng-shui/tong-shu/" description="The twelve day officers and the twenty-eight mansions." />
</CardGrid>

## What is computed

| Family | Endpoints | State |
|---|---:|---|
| BaZi: pillars and analysis | 18 | The full classical apparatus |
| Chinese calendar, zodiac, feng shui and Tong Shu | 15 | Derived from the ephemeris; the five feng-shui paths and the two Tong Shu ones are inside this 15 |
| Zi Wei Dou Shu | 14 | Star placement is computed; eleven reference routes stay reference |
| I Ching | 6 | Hexagrams, coin throw, changing lines |

<Aside type="note" title="Zi Wei Dou Shu: what is computed and what is a glossary">
`POST /v1/ziwei/chart` computes the whole chart: the soul and body palaces, the five-element class, the fourteen main stars, the auxiliaries, the twelve life stages, the decade limits and the 四化 on the stars that carry them. Eleven routes (`/ziwei/palace-*`, `twelve-palaces`, `main-stars`) stay reference tables with a `computed: false` field at half the standard rate. `/ziwei/full-chart` is deprecated in favour of `/ziwei/chart`.
</Aside>

## Localisation

The animals, the five phases, yin and yang, the palaces and the twelve life stages are translated into 21 languages. Stems, branches, star names, na yin and the twenty-eight mansions are **not** translated: their international name IS the pinyin beside the character, and inventing a Czech word for 甲 would be worse than leaving it. Same rule as the Human Design block.

```bash frame="terminal"
curl -X POST https://api.astroway.info/v1/bazi/chart \
  -H "X-Api-Key: aw_live_..." \
  -H "Content-Type: application/json" \
  -d '{ "date": "1990-05-15", "time": "14:30:00", "timezoneOffset": 8, "language": "en" }'
```