Ever been told to mind your p’s and q’s? Unless you were working a mechanical printing press at the time, chances are you were fairly subtly being told to mind your manners. But what exactly are your p’s and q’s?

The short answer is that no one really knows. But just because we don’t have a definitive answer doesn’t mean that we don’t have any answers at all. In fact, there are a number of competing theories as to what the original p’s and q’s might have been, some of which are a lot more convincing than others.

The Basic Politeness Theory

Probably the most widely held explanation also happens to be the most straightforward: “p’s” sounds a bit like “please,” “q’s” sounds a bit like “thank yous,” so to mind your p’s and q’s ultimately means “to mind your good manners.” It’s a neat idea, but it’s not a particularly reliable one. Unfortunately, there just isn’t enough textual evidence to support it, which suggests this is probably a relatively recent bit of folk etymology, based on the modern interpretation of the phrase p’s and q’s. So if this isn’t right, what is?

The Scribal Abbreviation Theory

A much less well-known explanation suggests that your p’s and q’s might actually have their origins way back when handwritten Latin documents were still being widely compiled and interpreted. Latin is a tough enough language to get your head around at the best of times, but in the Medieval period scholars and scribes were seemingly determined to make things even harder. In the interests of keeping their texts brief and compact, an elaborate system of scribal abbreviations was employed that saw various combinations of dots, dashes, bars, hooks, tails, stars, and other flourishes and embellishments attached to letters as abbreviations of lengthier words. Anyone reading these texts would have to be careful to interpret these symbols correctly, or else risk misreading or mistranslating—and because P and Q were among the most commonly embellished letters of all, that would naturally involve minding your p’s and q’s.

This is another neat idea that unfortunately falls down both through lack of evidence, and given the fact that the most complex of these scribal abbreviations had long since fallen out of use before the phrase p’s and q’s first appeared in the language. But when exactly was that?

The Pigtail and Overcoat Theory

The earliest record we have of someone’s p’s and q’s comes from a snappily-titled Jacobean stage play called Satiromastix, or The Untrussing of the Humorous Poet written by the English playwright Thomas Dekker in 1601. The line in question reads, “Now thou art in thy Pee and Kue, thou hast such a villanous broad backe.”

Both Dekker’s unusual spellings (pee and kue) and his equally unusual phrasing (“in your p’s and q’s”) has led to suggestions that the original p’s and q’s might have been items of clothing—namely, a sailor’s pea-coat or pea-jacket (a kind of thick, loose-fitting overcoat) and a queue or queue-peruke (a long plait of hair that was once a popular fashion accessory among high-ranking naval officers). But how does a sailor’s pea-coat and a naval officer’s wig give us a phrase meaning “mind your manners”? That’s a good question, and it’s not one that can be sufficiently answered—unless, of course, we’ve only got things half right…

The French Country Dancing Theory

Forget the pea-coat for a second. Imagine instead that you’re wearing your favorite queue-peruke while simultaneously learning to dance a courtly French jig. You’d understandably have to be careful not to hit the other dancers in the face with the tail end of your peruke as you were paying close attention to your feet. And the French word for foot? Well, that’s a pied. So all in all you’d have to mind your pieds and queues.

If this explanation all sounds a bit too contrived, you’re quite right to be suspicious of it. There’s no record of pieds and queues in any other context in English, and queue hairpieces really didn’t come into fashion in England until the early 18th century—that’s more than 100 years after Dekker’s play. Speaking of which…

The Let’s All Have A Drink Theory

In 1607, five years after the publication of Satiromastix, Dekker published another play called Westward Hoe. It contains the line, “at her p. and q. neither Marchantes [merchant’s] daughter, Aldermans wife, young countrey Gentle-woman, nor Courtiers Mistris [mistress], can match her.” Same author, same phrase. But very different spelling.

The Oxford English Dictionary points out that the fact that Dekker uses periods after the p. and q. in this line suggests that they might originally have been abbreviations—in which case the pee and kue he used five years earlier might just have been phonetic spellings, like aitch or em. But if p. and q. is really an abbreviation, what does it stand for?

According to the The English Dialect Dictionary, p and q means “prime quality”—but that explanation doesn’t quite account for the “and” that separates them, and so is probably another later invention. One unlikely idea is that they stand for penta and quinque, the Greek and Latin words for “five,” which would make the original p’s and q’s a classicist’s reminder that Greek and Latin word roots should never mix. Much more likely is that p and q stands for “pints and quarts,” in which case the phrase might originally have referred to a landlord totting up a customer’s tab, or to a drinker being told to mind how much they’re putting away. Or, given that there are four pints in a quart, perhaps the original implication was something along the lines of “take care of the little things, and the big things will look after themselves.”

The “pints and quarts” theory is plausible, but even the OED admits that it can “neither be substantiated nor dismissed.” Perhaps the most likely solution, then, is one of the simplest.

The Handwriting/Typesetting Theory

This is the explanation Merriam-Webster sign up to: children being taught to read and write commonly mix up their lowercase p’s and lowercase q’s, so telling them to “mind their p’s and q’s” means telling them to be extra careful, so as not to make a mistake. Similarly, another theory suggests that the original p’s and q’s might have been the individual pieces of moveable type used back in the early days of printing, when typesetters (who would be working with the letters back to front) might easily mistake a lowercase p for a lowercase and ruin an entire page of printed text.

There is at least some evidence to support the theory that the p’s and q’s you’re being told to mind are nothing more than the letters of the alphabet. The OED, for instance, cites a half dozen examples of the phrase p’s and q’s being used in an extended sense to mean essentially “your ABCs”, but problematically the earliest reference they’ve so far found in this context only dates back to 1763, whereas Dekker was writing in the early 1600s.

Not only that, but Q is one of the least used letters of the alphabet—presumably a child (or a typesetter, for that matter) is much more likely to confuse more common letters of the alphabet, like d and b or t and f than they are p and q? Why would that become the established expression? Despite these reservations, however, this final theory looks to be the most likely explanation on offer—at least, until another theory comes along…