Dust you are, and unto dust you shall return, said the Lord God to Adam after the first sin. Its a fine translation of the Hebrew, that dust; it suggests transience and insubstantiality. By the nineteenth century, in Britain at least, the word came to denote garbage of any sort. So Mr. Boffin in Dickens Our Mutual Friend is called The Golden Dustman because he has inherited several enormous mounds of dust, apparently worth a great deal. The first time I read the book, I wonderedwhat on earth could be so valuable about dust? We would now call it trash, as Shakespeare did. Who steals my purse steals trash, says the evil Iago, and thats a phrase that strikes the British ear as decidedly quaint. The boy in the back row sniggers. Trash? Wha in all Lonon is trash?
The word is a distant cousin of ancient Greek thymos, meaning spirit, not in the sense of ones soul, but rather what wed call drive, ambition, fire. How do we get from there to here? Grimms Law helps, as always. Grimms Law says that if you sprinkle fairy dust over your shoulderno, it doesnt say that. It relates the Proto-Indo-European th to Germanic d. In one of these essays Ill explain why. So what shows up in Greek and Latin as th will reliably show up in Germanic as d. Hence all we have to account for now is the nasal consonant m.
But wait! says a homeschooled lad in the sixth grade. You mentioned Latin th. But there arent any original Latin words with a th. Everybody knows that! Quite so, young man. And that requires explanation. When a sound should show up in a language but doesnt, we have two ways of accounting for the absence. One is that the sound simply dropped out. People found it hard to say, maybe, or they figured they could do without it, or nearby speakers of a different language didnt use it: so we no longer pronounce the k in knee. The other is that the sound was transformed into another and somewhat similar sound. Children help us out here. When my son was a very little boy, hed say fin for thin and vat for that. He was substituting a labiodental unvoiced spirant (f) for the interdental unvoiced spirant (th). That sure clears everything up! Try it, though, and youll see how it could happen. The Romans had no words beginning with th, but they did have a lot of words beginning with f, not all but some of which corresponded to Greek words in th. So then: Greek thymos = Latin fumus, smoke; English fume comes from the French, in the Middle Ages.
Back to dust: what happened to the m? Well, we know it was there, but by the time of Old English it had dropped away. But the Germans, a little more isolated, preserved the nasal consonant: Dunst: dust, mist, fume. All of which suggests a revision to the old folk song:
Are you going to Scarborough Fair?
Parsley, sage, rosemary, and dust
No, it doesnt work for me either.