Tang poetry · three readers · one anthology, every test counted

The Tone That Went Missing

Tang regulated verse sets level tones against oblique ones by rule. Score the 213 quatrains and octaves of Three Hundred Tang Poems with the rhyme book of 1008 and the rules hold on 97% of tests; read them in Cantonese and they hold on 96%; read them in Mandarin and more than one test in ten fails. Nearly every failure Mandarin adds falls on the entering tone, the syllables that once ended in -p, -t or -k.

Seven level tones in a row

This is Du Fu's poem on hearing that the government armies had retaken Henan and Hebei, 聞官軍收河南河北. Each square is one syllable, shaded by its tone class: level (平) or oblique (仄). The three buttons swap the reader. The first is the Guangyun, a rhyme dictionary compiled in 1007 and 1008, which files every character under one of the four tones (some under more than one). The other two are how a Cantonese speaker and a Mandarin speaker read the same characters today. The outlined squares are the positions the rules care about, and a red border marks a rule the reading breaks.

Under Mandarin, the seventh line, 即從巴峽穿巫峽, comes out as seven level tones. Three of its syllables (即, 峽, 峽) are in the entering tone in the rhyme book, and Mandarin now says them with a rising tone, which counts as level. In the rhyme book the line passes every test that can be scored on it; the rule was built for a tone Mandarin no longer has. The Mandarin reading breaks three more rules on 看, “look”, in line 3, which both modern readers give an oblique tone (kàn in Mandarin, hon3 in Cantonese). The rhyme book lists 看 in both the level and the departing tone, so those three are left out of the count below.

What the rules ask

The four tones of Middle Chinese were called level, rising, departing and entering. Poets sorted them into two: level (平) on one side, and the other three, together called oblique (仄), on the other. Regulated verse (近體詩, the quatrain 絕句 and the eight-line 律詩) is defined by how those two alternate. The mnemonic says “一三五不論，二四六分明”: the first, third and fifth syllables do not matter, the second, fourth and sixth must be clear. The rules scored here are the textbook ones, as the Chinese Wikipedia states them.

• R1, within the line: the second and fourth syllables differ, and in a seven-syllable line the fourth and sixth differ too.
• R2, opposition (相對): the two lines of a couplet have opposite tones in their second syllable.
• R3, adhesion (相黏): the first line of each later couplet has the same tone in its second syllable as the line before it.
• R4, rhyme: the even-numbered lines end in a level tone.
• R5, the unrhymed lines: the odd-numbered lines after the first end in an oblique tone.

Those five rules fix fewer syllables than they seem to. Pick the tone of the first line's second syllable and whether the first line rhymes, and they settle the rest of what they touch in a quatrain. Everything dashed below they leave free.

All 213 quatrains and octaves

Three Hundred Tang Poems was compiled around 1763 by Sun Zhu and sorts its poems by form. Its four sections of five- and seven-syllable quatrains and octaves hold 213 poems, scored here as regulated verse, and every one of them fits the scoring. The old-style sections (古詩) are the control: many of the same poets, the same dynasty, and no tone rule. Some tests cannot be scored by every reader: a character listed in both a level and an oblique tone in 1008 (看, “look”, is one) could be either, so the table counts only the tests that all three readers can score. That leaves 3,396 of the 4,354 regulated tests.

In the regulated poems the rhyme book and Cantonese agree to within two points on every rule. Mandarin loses between eight and ten points on every rule except the rhyme, where it loses nothing. In the old-style poems the adhesion rule holds 54.9% of the time, close to what a coin would give: the rules are real, and they belong to the form, not to the language. One thing the control did not show was indifference to opposition: old-style couplets still set their second syllables against each other 79.0% of the time.

Where Mandarin breaks, and why

Of the tests that pass in the rhyme book and fail in Mandarin, 246 of 253 involve a syllable whose tone in 1008 was entering, and in 245 of them that syllable is the one Mandarin moved into the level class. (In the other, 莫 kept an oblique tone and 場 beside it changed.) In the regulated poems 984 syllables have only an entering reading. The Mandarin reader gives 368 of them a level tone and 615 an oblique one (and leaves one toneless). The Cantonese reader gives all 984 an oblique reading, because every one of them still ends in -p, -t or -k.

That the entering tone makes regulated verse misbehave in Mandarin is not news. The Chinese Wikipedia's article on the tone classes gives the standard example, the first line of another poem by Du Fu:

“由於現代标准官話裡沒有入聲，因此用現代标准官話唸詩，可能會出現「平仄不調」的情況。在以上例子中，雖然「國」字屬於入聲，但在現代标准官話裡卻是陽平聲（第二聲）。”

zh.wikipedia.org, 平仄 (fetched 2026-09-29). In English: because modern standard Mandarin has no entering tone, reading poems in it can make the tones come out wrong; 國 is entering, but in Mandarin it has the second tone, which is level.

Their example falls on the first syllable of the line, one of the positions the mnemonic leaves free, so it breaks nothing the rules check. What this page adds is the count at the positions that are checked, over one whole anthology, with the control and the second modern reader beside it.

What the rhyme book does not explain

The rules do not hold on every test even in 1008, and each kind of miss is worth seeing.

• Quatrains that rhyme on oblique tones. Nine poems in the anthology's five-syllable quatrain section rhyme on oblique tones throughout, which makes 18 of the 22 rhyme failures. Among them are Wang Wei's 鹿柴 and 竹裏館, Meng Haoran's 春曉, and Liu Zongyuan's 江雪, which rhymes on entering-tone words (絕, 滅, 雪). They sit in the quatrain section, but the tradition does not count every quatrain as regulated: the Chinese Wikipedia calls the older kind 古絕 and describes it as freer in form, without strict metrical rules, and often rhymed on oblique tones (“形式較為自由，並無嚴格的格律限制，常有押仄聲韻的作品”). The pre-registration scored every poem in the quatrain sections as regulated, so they stay in the count.
• A copying error. Three rhyme failures are the text, not the poet. The digital edition used here prints 幹 (“trunk”, departing tone) where the poems have 乾 (“dry”, level) in 逢入京使, 月夜 and 無題 (相見時難); Wikisource has 乾 in all three. The same error turns the place name 長干 into 長幹 in two other poems. Put those five characters back and the rhyme rule goes from 561 to 564 of 583. The table above keeps the text as it came, because that is what was pre-registered.
• One gap in the data. The last rhyme failure is 漫, in Meng Haoran's 早寒有懷, which the rhyme-book data used here lists only in the departing tone.
• A licensed shape. Of the 67 within-line failures, 26 end in one shape: an odd-numbered line whose last three syllables run oblique, level, oblique, the ending of what the tradition allows as the “first special form”, (仄仄)平平仄平仄. Only 21 of the 26 fit that form as the source describes it: in 江雪 the first line rhymes, and four begin with an oblique syllable where the form wants a level one. Nine more would end in the shape if an ambiguous syllable is read oblique. The rest include old-style quatrains, Li Bai's 靜夜思, and the line 黃鶴一去不復返 in Cui Hao's 登黃鶴樓.

Poems that break no rule on the tests all three readers can score: 151 of 213 in the rhyme book, 136 in Cantonese, 65 in Mandarin.

What was predicted, before the count

The predictions were committed at 10:26 UTC on 29 September 2026, before any rate was computed, and are scored here as written.

• P1 · PARTLY FAILED. Regulated verse in the rhyme book: R1, R2 and R3 each at least 95% (held: 95.5, 98.7, 96.7), and R4 at least 98% (failed: 96.2, for the reasons above).
• P2 · PARTLY FAILED. Old-style verse in the rhyme book: adhesion at most 70% (held: 54.9) and opposition at most 75% (failed: 79.0).
• P3 · HELD. Mandarin between 5 and 20 points below the rhyme book on R1, R2 and R3: 8.4, 9.2 and 8.5 points.
• P4 · HELD. Cantonese within 3 points of the rhyme book on the same three: 0.6, 0.6 and 1.1.
• P5 · HELD. At least 80% of the Mandarin-only failures involve an entering-tone syllable: 246 of 253, 97.2%. The other seven: 場 read chǎng (four tests), 值 read zhí, which the data lists only in the departing tone (two), and 俱 read jù, a level tone that became oblique (one).

What this does not show

The rhyme book is not a recording. The Guangyun is a revision of the Qieyun of 601 and records which characters rhymed and which tone each was filed under; it does not say how the tones sounded, and their pitch is now hard to determine. The three readers are software: the rhyme-book reader is the qieyun package's Guangyun data, and the two modern readers are dictionaries that choose one reading for each character from its context. They make mistakes, and some show here: the Mandarin reader reads 乾 “dry” as qián, and where the Cantonese reader and the rhyme book disagree on a character, the commonest case is 斜 read ce3, which may be the software's reading rather than any speaker's. A character the rhyme book lists in both classes is never scored, which removes the hard cases along with the easy ones: 看 in Du Fu's third line is one, and both modern readers read it oblique where the rule needs it level. Thirteen characters could not be found in the rhyme-book data even through their variant forms and are not scored. The anthology here is one digital edition of one anthology.

Sources

1. 唐詩三百首, in chinese-poetry/chinese-poetry, 蒙学/tangshisanbaishou.json, commit b8594f81 (MIT licence). GitHub.
2. nk2028, qieyun 0.13.5 (CC0), a JavaScript library for the Qieyun phonological system; its data project describes its Guangyun table as the 澤存堂 edition with corrections. npm, data.
3. CanCLID, to-jyutping 3.1.1 (BSD-2-Clause). npm. And pinyin-pro 3.29.4 (MIT). npm.
4. Unicode Consortium, Unihan database, Unihan_Variants.txt, Unicode 18.0.0, for the variant forms. unicode.org.
5. Wikipedia (Chinese): 近體詩, 律诗 (the special forms) and 平仄 (the Mandarin example), fetched 2026-09-29. 近體詩, 律诗, 平仄.
6. Wikipedia (English): Four tones (Middle Chinese), Checked tone, Guangyun, Three Hundred Tang Poems, fetched 2026-09-29.
7. Wikisource (Chinese): 月夜 (杜甫), 逢入京使, 無題 (相見時難別亦難), 長干行二首, 長干曲其二, for the five corrected characters, fetched 2026-09-29.