Has anyone ever advised you to "mind your p's and q's"? If you were in England, they meant to be on your best behavior, and if in America they meant to pay close attention. They probably did not mean to watch out how you set your type for a printing press, but that is the origin of that phrase.
We actually get a good number of words and phrases borrowed from the print shop. The book Printer’s Error: Irreverent Stories from Book History is an entertaining history of printed books, authors and printers that gives us many examples.
One example is "minding your p's and q's" which is a phrase that comes from the printing process in the days past when physical movable type was used in a printing press.
I actually had the opportunity in my youth to set some type for printing. Setting type means placing each individual metal letter or symbol in a tray backward, so that when the inked type is pressed into paper, the mirror image reads the right way forward.
This was the job of compositors who had to be very careful setting up lines and pages of type - especially when it came to letters that look like mirror images of each other.
In older type cases (such as the one seen above and below), each letter was kept in its own section to be picked out by the compositor. The letters "b" and "d" could be confusing, but the lowercase p’s and q’s were right next to each other. "Mind your p’s and q’s” quite literally meant to be careful with those letters.
In that type case. all the capital letters are on the top or in a second upper case. The ones in the lower part of the case are what we began to call lowercase letters.
|Upper and lower cases of type|