Posted by Robert on February 26, 2003
In Reply to: Mind your p's and q's posted by hwttdz on February 21, 2003
: I don't have the text but I'm certain that it's from the moveable type explanation.
always heard that it meant "pints and quarts", referring to beer or ale.
I found these explanations at the site listed below.
The phrase dates to the late
18th century--at least 1779. The exact origin is unknown, but several competing
hypotheses seem to be the most likely. The first is that it derives from the phrase
p and q which was an abbreviation for "prime quality". This English dialectical
term dates to the 17th century. So to mind your p's and q's would mean to be quite
exacting in detail and ensure high quality.
The second is that it refers to difficulty children had in learning to distinguish between the letters p and q, being mirror images of one another. To mind one's p's and q's is a phrase meaning to learn one's letters is first recorded around 1830--somewhat later than 1779 but not impossible as the origin. Often this explanation is identified with printers and distinguish between a p and a q in type as we'll see below, but the early use exclusively deals with children learning at school and not printing.
The third possibility, first suggested by Farmer and Henley at the turn of the 20th century, is that the phrase comes from the practice of maintaining a tally (nowadays a bar tab) in pubs and taverns. Marks under column p, for pint, or q, for quart, would be made on a blackboard. To mind them would be to watch to ensure that the bartender did not allocate someone else's drinks to your tab or to mark a pint as a quart.
The last is from the world of printing. Typesetters had to be very skilled in reading letters backwards, as the blocks of moveable type would have mirror images of the letters. The lower-case letters p and q were particularly difficult to distinguish because they are mirrors of one another. Typesetters had to be particularly careful not to confuse the two when laying out the page.