It makes me think of the classic Donald Rumsfeld quote:
"Reports that say that something hasn't happened are always interesting to me because as we know, 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."
—United States Secretary of Defense, Donald Rumsfeld, Feb. 2002