After three hours of nuclear conflict we go headfirst into the unknown.
Andre Beaufre in Paul Virilio, Bunker Archaeology, 1975
As we know, there are known knowns; there are things that we know that 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.
Donald Rumsfeld, "On Defense," 2002