Lyndon Johnson could be vulgar to the extreme, giving interviews while sitting on the toilet with the door open, pulling up dogs by their ears, exposing his stomach to show a scar from an operation.

The Kennedys were notorious for their fickleness when it came to the press, courting favorites, then dismissing or ostracizing them at the first sign of criticism or disagreement. They hid their dedication to philandering behind a facade of good will. Woodrow Wilson, dismissive of the press at times, also worked to court favor with powerful publishers like E.W. Scripps.

Dwight Eisenhower and Barrack Obama were aloof. George H.W. Bush was condescending, beneath it all a president raised in an atmosphere of snobbery — not unlike Thomas Jefferson, who despite his upbringing saw the absolute importance of a free press.

All these men and indeed every president until now have had two things in common. They tried as hard as they could to manage the flow of news and those who control it while at the same time openly reaffirming their belief in the Fourth Estate no matter how frustrated they were by its zealousness. None of them condemned the entire institution as has the current occupant of the Oval Office.

Why? Because they swore to defend the Constitution, whose First Amendment has guided this nation since the beginning. Even more important, they understood that curtailing the people’s right to know is the first objective of every authoritarian government. Once a free press goes away, the rest of bedrock liberty — freedom of religion, speech and peaceable assembly — soon disappears too.

In the months Donald Trump has called himself president, evidence has piled up indicating he not only is unaware of his responsibilities to the Constitution but that he is fully capable of shredding the dignity of the office he holds to get his way. His recent video-attack showing him as a wrestler undoing a nemesis, CNN, was a silly and sophomoric attempt to play to the mob that elected him and stimulated his campaign rallies with “lock her up” cries befitting the French Revolution.

What really seems to be occurring in this display of little boy pique with its “fake news” theme is an attempt to distract Americans from a lack of campaign-promised achievement and understanding of the job.

But when do verbal attacks cross into “kill the messenger” territory? It’s worth asking in this age of unfettered firearms and online hate. One need only think of the violence committed against journalists around the world to imagine the worst.

Every American understood Harry Truman’s threat to thrash a critic whose opinion of his daughter’s singing was less than kind. It was a father defending his daughter. But there is no comparison here with Trump’s diatribes.

In 65 years in journalism, I have tried to treat criticism as the right of the reader and to admit mistakes openly. I have been sued only once, and the judge directed a verdict of innocence. I truly believe that most of the men and women who have been my colleagues have diligently tried to hold themselves to the same standards.

At the same time, I am not naive to the fact that we are not perfect in our effort to be the watchdogs of liberty. Our opinions do creep into our news columns, we are shrill and sometimes unfair in our dislikes, and yes, we’re even frequently guilty of political bias.

But flawed or not, we are necessary to a free society.

Trump should get on with the business of trying to run the country, accepting criticism for what it is, perhaps even showing some civility and dignity in the process. Those two traits, above all others, are absolutely necessary for holding the nation’s top office.

Dan Thomasson is a columnist for Tribune News Service.