In the closing of an English L&U question, one of our users, Cerberus, used what I'm sure is a marvelous construction full of history, pur sang, as in:
"...he is trying to argue here why it should mean something other than it does, which is argumentative pur sang."
Now I know "sang" means blood in Latin, and "pur" probably means "in order to" or something, but I don't get the feel of this phrase by breaking it down into its constituents. What does pur sang mean in this context? Is there a particularly famous literary usage?