Jiaobei Moon Blocks (擲筊)

Two Blocks, One Question — the Temple's Everyday Oracle

Overview

Walk into any temple from Tainan to Penang and you will hear it: the clatter of two crescent blocks on stone. Jiaobei — moon blocks, poe — is the most-performed act of divination in the Sinophone world, the ritual by which millions put a plain yes/no question to a deity every day. Each block has one flat face and one rounded one. Throw both: one of each means 聖筊, assent; two flat faces up means 笑筊, the deity smiles — your question is unclear, or the answer is already known; two flat faces down means 陰筊, no. For weighty matters the tradition demands 三聖筊 — three assents in a row — before a decision stands, and before any temple lot's verse is accepted, the blocks must approve the draw. askTIAN casts the blocks with honest physics: the outcome distribution is stated on every response (assent is exactly twice as likely as denial — the practice's built-in generosity), the three-confirmation protocol is implemented in its strict form with variants disclosed, and the rare standing block is honestly not simulated.

Origin & history

Block divination descends from the ancient practice of casting split bamboo roots and clamshells, formalized over centuries into the paired crescent blocks kept at every altar. The genius of the design is its asymmetric honesty: because each block distinguishes flat from round, the mixed outcome — assent — occupies half the probability space, while refusal and the smiling non-answer split the rest. The deity, in other words, is structurally inclined to encourage; only a clear no stops the asker. The 三聖筊 protocol raises the bar for serious matters: temple committees historically selected keepers and confirmed major decisions only on three consecutive assents, a practice still governing everything from festival dates to the acceptance of a drawn lot.

Jiaobei never needed revival — it is contemporary daily practice across Taiwan, Fujian, Hong Kong and the diaspora, from grandmothers asking after lost keys to corporations confirming groundbreaking dates. Serving it digitally demands the catalogue's usual honesty: the blocks here are fair (each face equally likely), the resulting 1/2 · 1/4 · 1/4 distribution is printed on every cast and locked by a four-thousand-throw statistical test, and the protocol conventions that vary between temples — chiefly whether a smiling throw merely re-asks or resets a confirmation streak — are disclosed rather than silently chosen. One thing is deliberately absent: the 立筊, the block that lands standing on its edge, held to be a powerful sign precisely because physics nearly forbids it. No principled probability exists for it, so this engine does not fake one.

How it works

Ask a question, optionally pass a seed for a reproducible cast, and choose a mode. Single mode throws once and answers: assent, denial, or the smile that asks you to rephrase. The threeConfirm mode runs the 三聖筊 protocol — throwing until three consecutive assents confirm the matter, the first denial ends it, and every smile resets the streak (the strict form; the gentler variant is named in the method string), capped at twenty throws with the tradition's own counsel returned if the matter stays unresolved. Every throw reports both blocks' faces, so the cast can be rendered block by block. The protocol's semantics are simulation-proven in the test suite: confirmed casts end at the first triple, denials end at the first 陰筊, and streak-resets are verified across hundreds of seeded runs. Deterministic, pure compute, no LLM — and one TIAN, priced for the everyday question.

Good for

Use cases

The Block Throw

One call, two blocks: animate the faces from the response, land on 聖筊/笑筊/陰筊, and show the tradition's reading — the fastest, most familiar oracle interaction in the Chinese-speaking world.

The Lot Confirmation

After divination.draw returns a lot, require a jiaobei assent before revealing the verse — the exact flow of a Taiwanese temple, now reproducible in two API calls.

The Weighty Question

Route serious questions to threeConfirm mode: the throw-by-throw drama of chasing three straight assents, with the strict protocol semantics guaranteed by tests.

The Honest Oracle Lesson

Surface the probability note as UI copy — an oracle that tells you it is structurally inclined to say yes is an oracle users can trust about everything else.

Key terms

聖筊 (Shèngjiāo)
Assent — one flat face up, one round: the deity says yes. Probability 1/2 with fair blocks.
笑筊 (Xiàojiāo)
The smile — both flat faces up: the question is unclear, premature, or already answered; ask again. Probability 1/4.
陰筊 (Yīnjiāo)
Denial — both flat faces down: no. Probability 1/4.
三聖筊 (Sān Shèngjiāo)
Three consecutive assents — the confirmation standard for weighty matters; the first denial ends the matter, and a smile resets the streak in the strict form served here.
立筊 (Lìjiāo)
The standing block — traditionally a sign of unusual force. Physically near-impossible, probabilistically unprincipled, and honestly not simulated.
The Built-in Generosity
Assent occupies half the outcome space — exactly twice denial's share — a structural feature of the two-faced blocks, stated on every response.
The Lot Pairing
In temple practice the blocks confirm a drawn lot before its verse is accepted — the two-call flow with divination.draw documented in every response.
Protocol Variants
Temples differ on whether 笑筊 resets a confirmation streak; the strict form is served and the variant disclosed, never silently merged.

API

The askTIAN Jiaobei API throws two fair moon blocks with both faces returned per throw, states the 1/2 · 1/4 · 1/4 outcome distribution on every cast (locked by a 4,096-throw statistical test), implements the 三聖筊 protocol in its strict form with variants disclosed and semantics simulation-proven (first triple confirms, first denial ends, smiles reset), honestly declines to simulate the 立筊, and documents the lot-confirmation pairing with divination.draw. Deterministic under seed. Pure compute, no LLM, 1 TIAN.

Endpoint: POST /trpc/jiaobei.cast — 1 TIAN Points. See the API documentation and Playground.