Badgered by Welsh rarebits and other red herrings

Readers probably remember the old nursery rhyme from their childhood: "Ring-a-ring of roses, A pocket full of posies, Tish-oo, tish-oo, We all fall down." They probably remember, too, being told that the rhyme is a very ancient one, which survives from the 1660s. Far from being an innocent children's rhyme, it refers to the Great Plague. The roses are the circular rash that was the first symptom of the disease; the posies were the futile attempts to keep off the infection with a nosegay of herbs. Unstoppable sneezing heralded the final stages, and in the end, well, we all fall down.

Readers probably remember the old nursery rhyme from their childhood: "Ring-a-ring of roses, A pocket full of posies, Tish-oo, tish-oo, We all fall down." They probably remember, too, being told that the rhyme is a very ancient one, which survives from the 1660s. Far from being an innocent children's rhyme, it refers to the Great Plague. The roses are the circular rash that was the first symptom of the disease; the posies were the futile attempts to keep off the infection with a nosegay of herbs. Unstoppable sneezing heralded the final stages, and in the end, well, we all fall down.

A nice explanation. But complete rubbish. There is absolutely no evidence whatsoever that the rhyme refers to the plague. The rhyme is not recorded anywhere or in any form before 1880, and does not reach anything like its modern form before the turn of the century. No 1660s writer on the plague mentions sneezing or red spots, although there is a comment in Thomas Vincent's 1666 tract, God's Terrible Voice in the City, that roses became unpopular, "lest with their sweet savour that which is infectious should be attracted."

The spread of colourful but erroneous explanations is a subject deserving of academic study in itself. Sir Thomas Browne, in the 17th century, devoted an enormous and fascinating book to mistaken beliefs about the natural world, Pseudodoxia Epidemica. It's a very funny book; my favourite passage is his earnest explanations to the reader that badgers, despite what Aristotle believed, do not have two legs shorter on their left side than their right to facilitate walking round hills.

Some of these beliefs are difficult to understand now. A simple mistranslation was responsible for the strange belief, visible in Michelangelo, that when Moses came down from Mount Sinai he had acquired a pair of horns. Surely somebody would have said, "Hang on, that can't be right"?

But before we indulge too much amusement in the odd beliefs of our ancestors, we might look at our own. Lemmings, for instance, don't jump over cliffs; they never have and never will. No evidence will stop someone, somewhere, from preferring a picturesque story to the obvious truth. You can explain Darwin to creationists until you are blue in the face, and they will still carry on thinking that on the fifth day, about ten to three in the afternoon, God created gerbils. My grandmother firmly believed that the combination of strawberries and vanilla ice-cream was deadly poison, and you could eat it in front of her and fail to die, and still not dissuade her.

Etymology, however, is the most amusing arena for these false beliefs. Everyone knows the explanation that the word posh stands for "Port Out, Starboard Home", according to which side of a ship travelling to India and back would be predominantly in the shade. Perfect nonsense, of course. But I heard an even more extravagant folk etymology recently. The story was that, on long sea voyages, English sailors became so sex-starved that they were allowed to have sex with each other on the King's birthday. The licence became known as Fornication Under Consent of the King, subsequently abbreviated...

What the motivation for such stories is, I don't know. Sometimes just a nice anecdote, seeking to explain something whose origins are, in reality, lost in obscurity; sometimes, by contrast, when the origins are all too clear, the intention is to spare the feelings by shrouding them in a mysterious delicacy.

This week's controversy over whether the cheese-on-toast dish should be referred to as Welsh Rabbit or Rarebit is a case in point. Rabbit, in fact, is the original form, as a glance at the OED will show. Like Scotch Woodcock, it started as arather offensive English joke about the poverty of their Celtic neighbours, and the euphemistic form Rarebit only took root in a more delicate era of history - I doubt it can be found before 1900.

It's quite a familiar development. The Jew's harp, at some places and times, became, euphemistically but incorrectly, jaw's harp. But it's easy to become convinced that something one once heard and habitually used must therefore be correct.

Frustrating as picturesque inventions can be to the historian, one wouldn't be without them. I've been told so many explanations of what the Roman vomitorium was, and indeed looked it up so many times, that I can't remember what it actually was: it never existed, it was merely the exit from the dining room in a villa, it was a special room where dinner guests went to be sick before returning and eating some more, or it was a sort of sideboard with handles, designed for the same purpose. One of the explanations must be right, though I can't remember which one; on the other hand, I think I rather like all the stories.

And especially the wrong ones.