The missing quadrant on that one is interesting too:

> "there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns—the ones we don't know we don't know."

The fourth corner is unknown knowns, things that we don't know that we know. Bureaucracies have that one in spades.