Pentagon briefings must be a lot of fun especially whent hey contain such jewells as this one allegedly by the US defence secretary Donald Rumsfield
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 don't know.
But there are also unknown unknowns,
The ones we don't know we don't know.
