referring to people who are the opposite of nouveau riche
A very refined idiom, I'd say, and one which praises accomplishments in an intelligent and friendly way. This said, having read Lenka's opinion:
The North could take their slaves but they couldn't take their pride
I should add that pride doesn't go well with slavery (or does it)?
Actually, there is a Polish idiom describing a somewhat reverse situation to that shown in Maf's idiom.