Discussion Forum—A Way with Words, a fun radio show and podcast about language

I don't recall running across "like chalk and cheese" or "as different aws chalk and cheese" before, but I ran into it on Discus, and thought that's a useful idion; I bet it's not original.

Ngrams has a dead line on "chalk and cheese" until 1802 or so when it starts picking up.  The oldest cite they have seems to be 1952's Thesaurus Linguae Latinae Compendiarius which describes itself as being primarily for the British nations.  The Phrase Finder says

There must have been a time in the development of English when we had no standard phrase to express the idea that two things were 'as different as X and Y'. When someone coined such a phrase, and that someone may well have been Gower in 1390, clearly he needed candidates for the roles of X and Y. That doesn't sound difficult, after all most things are different from most other things.

"Maybe, 'as different as a cormorant and a lamp-post'", thinks our coiner, "or 'as different as floorboards and greengrocers'". "No, 'as different as chalk and cheese' sounds better". Why? For no better reason that the fact the 'chalk' and 'cheese' are short and snappy words that alliterate. The English language is packed full of phrases that contain pairs of rhyming or alliterating words - often just because the person who coined them liked the sound of them; for example, hocus-pocus, the bee's knees, riff-raff etc.

Dick Francis' Decider, he has a jockey saying an architect isn't clever enough to design new stands for the horse track she is partial heir to.  He doesn't know the difference between a rabbit and a raceway.  Dogs chase a rabbit at Florida racetracks, but the jockey means the woodworking terms.  A rabbet is the step-shaped recess a tongue goes in, while a raceway is a channel in which something - a door perhaps - runs. It's a significant clue to the mystery, but it's interesting that the mystery is set in England, the characters are English and Francis is himself English (he used to ride the Queen Mother's horses), but rabbet is mostly a North-American term. 

I presume Francis fabricated the idiom.  Google doesn't chart any ngrams for eiither rabbit and raceway, or rabbet and raceway, and although I've  been waiting for years for the opportunity to say someone is so ignorant, they don't know the difference between a rabbet abd a raceway, the dolts I want to inisult wouldn't know what either is, much less the difference.  Would you insult a lousy cook by claiming he wouldn't know the stars on the Orion constellation?  "Oh, lack of depth, where is thy sting?"

But now, I'll be looking for an opportunity to toss in a comparison between cheese and chalk.  I don't think comorant and lamp-posts will work - particularly when I can't tell a comorant from a loon.