2017 may wind up being a terrible year for Donald Trump, but it's a very, very, good year for Richard Neustadt (1919-2003) and the theory of the presidency explicated in his 1960 classic, "Presidential Power."
What Neustadt taught was that the constitutional office of President of the United States is an inherently weak one, but that skilled presidents can nevertheless become enormously influential. The flip side of this, however, is that an amateurish president can barely even exercise the constitutional and statutory authority of the office. Neustadt introduces his topic by contrasting the presidency with the way the military appears to operate: