Why does Standard English use sing, sang, sung but not bring, brang, brung? And why is the song you sing the very same word as sing, just wearing a different vowel?
Most English verbs make their past tense the lazy way: bolt -ed on the end (walk → walked). A few hundred do something stranger and far older — they change the vowel in the middle of the word. sing · sang · sung. drive · drove · driven. These are the strong verbs, and the vowel-swap isn't random English messiness: it is ablaut, a system of vowel alternation inherited from Proto-Indo-European, six thousand years deep. Here it is, made runnable: a wall of verbs caught changing from the inside, the seven shelves the strong verbs sort onto, the o-grade hiding inside everyday nouns — and the slow, measured tide that keeps dragging these verbs back toward -ed.
Each row is a strong verb in its three principal parts — present, past, participle — the vowel doing the work the suffix does elsewhere. Touch one for the ablaut grades underneath, and the everyday noun that froze out of the same root. The last two rows are imposters: they look strong, but that final -t gives them away.
The strong verbs aren't a junk drawer of exceptions. Germanic philology sorts them onto seven shelves, with Classes I-V largely sorted by what follows the root vowel: a glide, a nasal, a liquid, a single consonant. Class VI is distinguished by its vowel pattern, Class VII by reduplication. The first six have characteristic patterns across the four old principal parts; Class VII has several patterns, not one fixed series. Pick a shelf.
The vowels shown are the reconstructed Proto-Germanic pattern (the asterisk marks reconstructions). Modern English forms have been battered by later sound changes — the Great Vowel Shift above all — so today's drive/drove/driven looks less tidy than its ancestor *drībaną / *draib / *dribun / *dribanaz. The shelf is about the deep pattern, not the modern spelling.
Here is the quiet astonishment. The same vowel-swap that turns sing into sang also turns the verb sing into the noun song — song is literally the o-grade of sing, frozen into a naming word thousands of years ago. Tap a verb to wake the noun that ablaut left behind.
Strong verbs are a closed, shrinking club. No new verb ever joins by birth — google, text, photoshop all went straight to -ed. And the old members keep defecting: help was once strong (healp, holpen), climb was clomb, chew had Old English past forms céaw, cuwon and participle cowen. One careful study put real numbers on the leak.
The tide isn't quite one-way. A few verbs with established weak forms grew a strong-looking past by analogy; the pattern still has a faint pull. (How faint: each of these is contested or regional, and none is a new class.)
Here is the test that separates a true strong verb from an irregular pretender. A strong verb marks its past with a vowel change and no suffix. A weak verb — even a wildly irregular one like brought or kept — always hides a dental suffix, a -t or -d, however much the vowel also moved. Find the -t/-d and you've found a weak verb in disguise.
Corrected 2026-10-14: The opening said 'never bring, brang, brung'. Brang and brung are attested nonstandard forms; the question now specifies Standard English; found by the assay line, 2026-10-14. Source.
Corrected 2026-10-14: The page called ablaut 'inherited intact' from Proto-Indo-European. Its ancestry is Indo-European, but the long past-plural vowel of Classes IV and V developed within Germanic; found by the assay line, 2026-10-14. Source.
Corrected 2026-10-14: The page said following sounds decide all seven classes. They largely distinguish Classes I-V; VI is distinguished by its vowel pattern and VII by reduplication; found by the assay line, 2026-10-14. Source.
Corrected 2026-10-14: The page said each class has one fixed vowel pattern. Class VII has several patterns; its four placeholders here do not represent a single vowel series; found by the assay line, 2026-10-14. Source.
Corrected 2026-10-14: The page labeled a mixed drive paradigm, including draif and dribans, as Proto-Germanic. The cited Proto-Germanic series is *drībaną / *draib / *dribun / *dribanaz; found by the assay line, 2026-10-14. Source.
Corrected 2026-10-14: The page gave chew/chowen as chew's old strong forms. Murray's dictionary gives Old English past céaw, cuwon and participle cowen; found by the assay line, 2026-10-14. Source.
Corrected 2026-10-14: The page said the analogy examples were 'always weak'. Dive has a strong Old English ancestor as well as a weak one, although dived preceded modern dove; found by the assay line, 2026-10-14. Source.
Corrected 2026-10-14: The page put bier in the o-grade list with bairn and barrow. Bier is related to bear through a lengthened e-grade formation; found by the assay line, 2026-10-14. Source.
Corrected 2026-10-14: The page identified the e-grade with the ending in giv-EN. The historical e-grade is the root vowel of geb- in *gebanaz; English -en is a participial ending; found by the assay line, 2026-10-14. Source.
Corrected 2026-10-14: The Class V panel said speak drifted into that class. Speak began in V and adopted Class IV-type spoke/spoken forms; found by the assay line, 2026-10-14. Source.
Corrected 2026-10-14: The page quoted Wiktionary as stating song's derivation 'outright'. The entry begins 'Perhaps an o-grade nominal'; the quotation and attribution now retain that qualification and mark omitted words; found by the assay line, 2026-10-14. Source.
Corrected 2026-10-14: The page quoted 'newly-wed'. Lieberman et al. printed 'newly wed', with a space and quotation marks around those two words. Their 4.2 figure is uses per million verbs; found by the assay line, 2026-10-14. Source.
Corrected 2026-10-14: The chart caption said it showed six frequency bins, but the chart contains five. It now describes five selected bins from the paper's six; found by the assay line, 2026-10-14. Source.
Corrected 2026-10-14: The framing called the noun from each displayed verb o-grade. Drift, bit and burden are labeled zero-grade; the framing now allows both grades; found by the assay line, 2026-10-14. Source.
Corrected 2026-10-14: The relation note said Grimm coined the very word ablaut in 1819. He coined its technical sense in 1819; the word had been used before him; found by the assay line, 2026-10-14. Source.
Corrected 2026-10-14: The legend labeled every past o-grade, although bound reflects the old zero-grade past plural. The colors now label grammatical forms; individual entries explain their grades; found by the assay line, 2026-10-14. Source.
Corrected 2026-10-14: The legend labeled every participle zero-grade, although Class V given descends from an e-grade participle. The colors now label grammatical forms; individual entries explain their grades; found by the assay line, 2026-10-14. Source.
Corrected 2026-10-14: The nearby note called adjective order a rule every English speaker obeys. The linked page reports strong preferences with exceptions; the note now says that; found by the assay line, 2026-10-14. Source.
Written 2026-06-30. Claims re-read against their sources on 2026-10-14: 280 checked, 245 confirmed, 35 wrong, 0 unverifiable. By the assay line (research/assay-line/cited-1014b/), Codex fixer directed by claude-assaying-boyle-1014; source record by Codex, checked by Codex.
This was the directed repair pass over all 35 items in research/assay-line/cited-1014b/sing-sang-sung/triage.json at f5e5f84f34, with the fixer re-reading the evidence before each edit. Thirty WRONG items share eighteen errors corrected within this layer; the Codex repair follow-up on 2026-10-14 confirmed two errors still copied in other layers, held below with PENDING board notes. Four listed MINOR items remain unchanged, and X9 is CONFIRMED because the proposed notation correction was rejected with independent evidence. The pass also fixes one MINOR verifier label. The 244 further CONFIRMED lines below retain the source checks and wording recorded by Codex in N2-codex.md at the pinned revision; they are the checker's re-reads, not a claim that the fixer independently repeated all 244. The five MINOR lines count in wrong, with their individual dispositions. Original claim punctuation encoded as \u2014 is retained as an escape, not as a literal character. No STALE finding was directed; dateModified advances for these corrections without an Updated line.
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