Good day to you. Missed us? Here is another etymological conjuring trick.
Have you had a proper look at the picture? A hippopotamus is eating cheese and washing it down with kvass. What have the three of them got in common?
The usual answer would be: a Proto-Indo-European root. This time *kʷeth₂-, “to boil, to ferment, to seethe.”
Two of them check out
Kvass—the sour, faintly fizzy rye drink of the Slavonic world, which turns up in nineteenth-century English translations of Russian novels as quass—comes straight off that root. Old Church Slavonic kvasŭ means “leaven, ferment, fermented drink,” and the family includes the Russian word for “sour.” No difficulty there: kvass is fermentation with a name on it.
Cheese is the surprise. Latin cāseus gave us the technical casein, gave the Spaniards queso, the Germans Käse, the Dutch kaas and the Welsh caws—and, borrowed early into Germanic, gave English its own cheese. And cāseus comes from the same *kʷeth₂-.
Which makes perfect sense the moment you think about what cheese is. Not a dairy product so much as a controlled spoilage: milk deliberately soured, curdled and left to its own devices. The Old Prussians called it keswan; the Slavs used the same root for their drink. A cheddar and a glass of kvass are, etymologically, the same event happening in different buckets.
And then there is the hippo
Here I must own up. When I first assembled this trio I had a theory about the hippopotamus, and the theory was wrong.
Greek ἱπποπόταμος is “river horse”: ἵππος “horse” (as in hippodrome) plus ποταμός “river.” And I had persuaded myself that the river in question was a bubbling, seething mountain torrent—that potamós belonged with our fermenting root, with the p arising from an earlier kʷ, exactly as Latin aqua became apă in Romanian.
It is a tidy story. It is also, on the evidence, not the received one. Most authorities derive ποταμός from a quite different root, *peth₂-, “to fly, to rush”—so that a river is not seething water but rushing water. And that root has a large and respectable English family: feather, pen, petition, appetite, helicopter, pterodactyl, and every winged thing in the etymological collection—which is, note, a quite different cabinet from the entomological one, however often the two get muddled. The Greek πίπτω, “to fall,” is a cousin; so is Latin penna, a wing.
So the hippopotamus is not a relative. He is an impostor, admitted to the family on the strength of a resemblance, and now exposed.
Which is the better joke anyway
Two of the three are genuinely kin: the cheese and the kvass, both of them fermentation wearing different clothes. The third simply looks as though he ought to be, and that is exactly how folk etymology recruits its members—by resemblance, confidently asserted.
The moral, as ever in this department: a plausible chain is not the same as a true one. And it is worth checking even when—especially when—the chain is your own.
The picture, though—Gemini did rather well with that.
