Presidential historian Jon Meacham did his best on Morning Joe this morning to lower the bar for President Obama's speech today commemorating the 50th anniversary of the March on Washington. "The country has put an enormous amount of expectation on him . . . since he first came on the stage in 2004 . . . we sometimes have-often have--unrealistic expectations of the office," empathized Meacham. Nice try. But wasn't it Barack Obama himself who raised expectations to absurd heights? Does this phrase ring a bell, Mr. Meacham?: "I am absolutely certain that generations from now, we will be able...