The Sound Shifts

The machine that predicts words.

In 1822 Jacob Grimm — yes, that Grimm — set out the rule by which the consonants of Proto-Indo-European shifted in the Germanic languages and nowhere else. It is why English has father from its own ancestors and paternal from Latin: the same word, once shifted and once not. Watch the rule run.

Grimm’s Law, 1822: the Proto-Indo-European stops shifted in Germanic — and only in Germanic. Latin, Greek and Sanskrit keep the old consonant, so the same root shows up twice in English: once inherited through Germanic (shifted) and once borrowed from Latin (unshifted). A K that became an H did not stop being the root. The instrument shows the root, the rule that applies, and both descendants.

Proto-Indo-European

*ph₂tḗr

father

Grimm’s Law

voiceless stop → voiceless fricative

Germanic

father

by inheritance

Unshifted — the old consonant kept

Latinpater
Greekπατήρ
Sanskritpitā́

Shifted — Germanic only

Englishfather
GermanVater
Old Norsefaðir

And borrowed back, unshifted

paternal
patron
patriot

The p stays in Latin and becomes f in Germanic. English has both: father by inheritance, paternal by borrowing.

Proto-Indo-European

*pṓds

foot

Grimm’s Law

voiceless stop → voiceless fricative

Germanic

foot

by inheritance

Unshifted — the old consonant kept

Latinpēs, pedis
Greekπούς
Sanskritpā́d-

Shifted — Germanic only

Englishfoot
GermanFuß
Gothicfōtus

And borrowed back, unshifted

pedal
pedestrian
podiatry

Same rule, same direction. Once you have seen it twice you can predict the third.

Proto-Indo-European

*tréyes

three

Grimm’s Law

tþ

voiceless stop → voiceless fricative

Germanic

three

by inheritance

Unshifted — the old consonant kept

Latintrēs
Greekτρεῖς
Sanskrittráyas

Shifted — Germanic only

Englishthree
Germandrei
Old Norseþrír

And borrowed back, unshifted

trio
triple
trinity

t becomes the th that English still writes with two letters because the alphabet it borrowed had no sign for it.

Proto-Indo-European

*ḱḗr

heart

Grimm’s Law

voiceless stop → voiceless fricative

Germanic

heart

by inheritance

Unshifted — the old consonant kept

Latincor, cordis
Greekκαρδία
Sanskrithṛ́d-

Shifted — Germanic only

Englishheart
GermanHerz
Gothichaírtō

And borrowed back, unshifted

cardiac
cordial
courage

The physician’s pair. Cardiac and heart are one word; medicine borrowed the unshifted one from Greek and left the shifted one to the patient.

Proto-Indo-European

*káput

head

Grimm’s Law

voiceless stop → voiceless fricative

Germanic

head

by inheritance

Unshifted — the old consonant kept

Latincaput
Sanskritkapā́la-

Shifted — Germanic only

Englishhead
GermanHaupt
Old Englishhēafod

And borrowed back, unshifted

capital
captain
decapitate

Cap-, chief, chef and head are all the same skull, seen from four languages.

Proto-Indo-European

*h₁dónts

tooth

Grimm’s Law

voiced stop → voiceless stop

Germanic

tooth

by inheritance

Unshifted — the old consonant kept

Latindēns, dentis
Greekὀδούς
Sanskritdánt-

Shifted — Germanic only

Englishtooth
GermanZahn
Gothictunþus

And borrowed back, unshifted

dental
dentist
indent

Voiced d devoices to t. The dentist and the tooth are the same word by two roads.

Proto-Indo-European

*ǵónu

knee

Grimm’s Law

voiced stop → voiceless stop

Germanic

knee

by inheritance

Unshifted — the old consonant kept

Latingenū
Greekγόνυ
Sanskritjā́nu

Shifted — Germanic only

Englishknee
GermanKnie
Gothickniu

And borrowed back, unshifted

genuflect
genuine

The k in knee is silent now, but it is the shifted g of genū, and English spelled it for centuries after it stopped saying it.

Proto-Indo-European

*bʰréh₂tēr

brother

Grimm’s Law

bʰb

breathy stop → voiced stop

Germanic

brother

by inheritance

Unshifted — the old consonant kept

Latinfrāter
Greekφράτηρ
Sanskritbhrā́tar-

Shifted — Germanic only

Englishbrother
GermanBruder
Gothicbrōþar

And borrowed back, unshifted

fraternal
fraternity
friar

Latin turned the breathy bʰ into f; Germanic turned it into plain b. So brother and friar are the same man.

Proto-Indo-European

*gʰóstis

stranger

Grimm’s Law

gʰg

breathy stop → voiced stop

Germanic

guest

by inheritance

Unshifted — the old consonant kept

Latinhostis

Shifted — Germanic only

Englishguest
GermanGast
Old Norsegestr

And borrowed back, unshifted

hostile
host
hospital

Latin made the breathy gʰ into h; Germanic made it g. Guest and hostile: the whole politics of the doorway in one consonant.

Why it matters here

A shift is a fingerprint, not a divorce.

Pēs and foot do not look alike; cor and heart do not sound alike. They are the same word, because a rule connects them, the rule holds across hundreds of words, and it predicts forms nobody had looked up yet. That is the mainstream’s own proof that a word can change every consonant it has and still be the word — and it is the fifth rule of the system.

The system applies the same logic without a border. When sh becomes s becomes z along the road that sugar travelled from Sanskrit to Spain, or k becomes h on the road from Latin to Spanish, the word did not stop being the word. A change that runs by rule is a family resemblance, and the season follows the resemblance across the family lines the textbooks drew.

One honesty about the machine. Grimm’s Law has exceptions, and in 1875 Karl Verner explained them — the shift depends on where the accent fell in the parent word. The demonstrations here are the plain cases. When an episode leans on a word Verner governs, the episode says so.

The machine that predicts words.

A shift is a fingerprint, not a divorce.

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