Once upon a time…

Once upon a time, there were two brothers who very much enjoyed stories. They travelled their country looking for folk tales, each one darker and grimmer than the last… There was no happily ever after in sight and, though their stories have changed much since, the original tales are still found out there for those brave enough to seek them…

Prepare yourselves, my dears, because this… this is the story of the brothers Grimm.


Or not! Actually, it is the story of one of the brothers: Jacob Grimm. And it won’t be grim in the least but full of fun linguistic facts!

Today, we’ll be talking about what is known as the First Germanic Sound Shift, Rask’s Rule or, most commonly, Grimm’s Law.

Riccardo touched upon this topic in last week’s post on the comparative method, a method that was pretty much born with this particular observation. The first to notice the correspondence that would eventually become Grimm’s Law was Friedrich Schlegel, a German philologist, in 1806. Rasmus Rask, a Danish philologist, extended the ‘rule’ to to other PIE languages in 1818 and, eventually, Grimm included German in his book Deutsche Grammatik, published in 1822.

Now, they noticed a regular sound change that affected certain Proto-Indo-European (PIE) consonants. They also noticed that this particular sound change only affected the Germanic languages, e.g. German, Dutch, English, Swedish, etc.

But what is it?

Well, Grimm’s Law describes how certain PIE consonants developed in Proto-Germanic, particularly early Germanic stops and fricatives. Now, you might want to refresh your memory on phonological terminology before continuing, but there can be said to be three parts of the chain shift that is Grimm’s law:

  1. PIE voiceless stops became voiceless fricatives
  2. PIE voiced stops became voiceless stops
  3. PIE voiced aspirated stops became voiced stops or fricatives.

That might be a bit abstract but it basically works like this:

p > f b > p bh > b
t > θ d > t dh > d
k > x g > k gh > g
> > ghʷ >


Consider these words in Latin, English and Swedish and compare them to their PIE root:


PIE² Latin English Swedish
*ped- pēs foot fot
*dwo- duo two två
*genu- genū knee³ knä

Now, why would English and Swedish have <f>, <t> and <k> where PIE and Latin have <p>, <d> and <g>?

Well, because English and Swedish, being Germanic languages, underwent Grimm’s Law and thus changed the PIE sound */p/, */d/ and */g/ to /f/, /t/ and /k/ respectively. Latin, on the other hand, is an Italic language and didn’t undergo this change, thus keeping the sounds of PIE (or at least approximately, though exactly how close these sounds are is a bit difficult to say with certainty).  

Why would this happen, you might wonder? What would make one sound shift to become another sound?

Well, we don’t really know exactly how it started or why. It might be what is called a ‘pull chain’, meaning that one sound shifts, leading to a ‘gap’ in the phonological values of the language. As a result, another sound shifts to fill that gap and a third sound shifts to fit the gap of the second one and so on and so forth.

But, it is also possible that it worked the other way around, meaning that one sound started to shift and basically pushed another sound out of its place, thereby leading to a chain shift. This is called a push chain.

But as to how such a chain started? Well, that part is still kind of shrouded in mystery. Perhaps two sounds became too similar to each other and became difficult to distinguish from each other, forcing a shift? We might never know.

What we do know, however, is that Grimm’s Law did affect all Germanic languages, leading to a distinction between that language family and its PIE-derived sisters.

But there are also a good number of exceptions from this rule. For example:

Why does PIE *bʰréh₂tēr (“brother”) become Proto-Germanic *brōþēr but PIE *ph₂tḗr (“father”) became Proto-Germanic *fadēr?

In ‘brother’, the development follows Grimm’s Law, i.e.  t > þ, but in ‘father’ it does not. Instead of the, by Grimm’s law, expected development, i.e. t > þ, the Proto-Germanic word developed t > d. Why is that?

Well, cue Karl Verner; a Danish linguist who in 1875 formulated what is now known as Verner’s Law, an addition, if you will, to Grimm’s Law. Verner’s Law explains such occurrences as ‘father’, showing that voiceless fricatives, e.g. *f, *s, *þ, when immediately following an unstressed syllable in the same word, underwent voicing and becomes fricatives, e.g. *β, *z,*ð

Now, you might be thinking that this is all very interesting but why is it important? ‘cause I can pretty much promise you, that if there is anything the budding historical linguist is aware of, it is Grimm’s Law.

Well, while it is fascinating in its own right, its discovery showed us something much greater than we had ever thought possible before: that sound change is a regular phenomenon, not a random process affecting only some words.

This discovery not only set historical phonology apart as its own field of study but also means that we can predict and understand phonological developments, a discovery that cleared the field for the comparative method.

And without the comparative method, of course, our field of inquiry would be so much poorer as we would largely be unable to properly understand the relationship between languages and the historical developments of those languages.

And wouldn’t we all be a lot poorer for that lack of understanding?

So, next time you watch Cinderella, Little Red Riding Hood or Hansel and Gretel, remember that Jacob Grimm not only provided you with these stories but helped design the most used, and important, method in historical linguistics to this day. Not a bad contribution, right?

Join us next week when our awesome magician Riccardo is back! This time, he’ll be talking about the magic of umlaut and ablaut, so if you’ve ever wondered why it’s ‘mouse’ but ‘mice’ but not ‘house’ and ‘hice’ you definitely don’t want to miss it.


Notes and sources

¹ PGmc is a common abbreviation for Proto-Germanic

² All the PIE roots can be found by a simple google search. These are taken from the Online Etymology Dictionary found here: https://www.etymonline.com/. Have fun!

³ Remember now that while the <k> in modern English ‘knee’ is silent today, it was pronounced in earlier stages of English.

*The little pic is from http://tentcampinghq.com/camping-articles/how-to-tell-scary-campfire-stories-2/

**For those who wants to know more about Grimm’s Law, most (if not all) introductory textbooks on linguistics deals with the subject at least a little bit. This particular illustration is from Millward, C.M. A Biography of the English Language.  Ft. Worth: Harcourt, 1996. Pg. 63 but a similar one can be found in pretty much any textbook. Particularly recommended is Lyle Campbell’s Historical Linguistics (3rd ed., 2012) which deals with most things historical linguisticky with great attention to detail and plenty of examples (so it’s recommended generally, not only for this particular sound change). 

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