Mind your Ps and Qs

In the spirit of word origins and history of expressions (as anyone who knows me will attest that I love) I bring you the expression of the day.

This phrase has more possible origins than any other -- and nobody knows just what to believe. The only thing everyone can agree upon is that the idiom was first cited by the Oxford English Dictionary in 1779 with the meaning of watching your step and being polite.

One simple explanation is that it's a childish abbreviation for minding your "pleases" and "thank yous." Considering how often kids are told to "mind your Ps and Qs" with the goal of being more polite, this explanation makes sense.

Two popular theories revolve around the mirror-image quality of the two letters. The phrase was recorded in 1830 as meaning "to learn one's letters." It was aimed at children learning to hand-write the lowercase letters p and q, which are quite similar. Another explanation along the same lines comes from the world of printing. Typesetters used blocks of type that were mirror images of the letters, so it would be easy to mix up lowercase p and q. This origin would give "mind your Ps and Qs" a connotation of being careful and paying sharp attention.

Another oft-mentioned source of the phrase is old pubs where beer and ale was served in pints and quarts. The barkeeper tracked patrons' drinking totals by marking "P" for pints and "Q" for quarts. Both the barkeeper and the drinker would want to keep careful track of those Ps and Qs so they knew what the final bill would be. Also, the drinker might want to pay attention to how much he drank so as to keep his own behavior under control.

World Wide Words notes that this puzzling and quirky idiom has inspired some fanciful explanations. In the 17th century, the expression "P and Q" meant "prime quality," which might have influenced the Ps and Qs phrase. Some suggest the saying came from a French dancing master's instructions to perform the dance figures pieds and queues properly. Or it could be an admonishment to sailors to keep their navy peacoats clean around their tarred queues or pigtails. But these derivations seem pretty far-fetched.