There are known knowns. These are things we know that we know. There are known unknowns. That is to say, there are things that we know we don't know. But there are also unknown unknowns. There are things we don't know we don't know.
Don't think of yourself as indispensable or infallible. As Charles De Gaulle said, the cemeteries of the world are full of indispensable men.
Don't blame the boss. He has enough problems.
I can't tell you if the use of force in Iraq today will last five days, five weeks or five months, but it won't last any longer than that.
The price of being close to the President is delivering bad news. You fail him if you don't tell him the truth. Others won't do it.