Trump has shown us the precedents and traditions surrounding the office of the presidency, and the competition to attain that office, are not enough to bring about respect and compliance by the occupant of the White House. Trump paradoxically seems to despise the traditions of the very office he sought.
Specifically, he has taught us that income tax returns of candidates and nominees must be revealed by law, not by custom. Trump has good reason to flout this tradition, the least of which is being under audit.
That's because his returns will probably show that his real estate empire was bailed out in 2008 by Russian banks, and that the Russian mafia has allegedly laundered millions through his holdings by buying his condos for above asking price.
Photos exist of Trump smiling alongside figures of ill repute. Nothing need be done to uncover this link. It is in plain sight. A responsible Congress - one that truly seeks to protect the welfare of the nation - would pass a law requiring full financial disclosure, both for the candidate and for any that she or he might subsequently nominate to positions of power.
Lesson No. 2: Flaws in electoral system
By winning the office with the largest vote deficit in history, 2.8 million or so below Hillary Clinton, Trump has taught us that the Electoral College is an anachronism whose original function, to weld together colonies with disparate populations, has never been served and whose impact today is positively deleterious.
The world now knows that the United States can no longer present itself as a paradigm of democratic process. In addition, the gerrymandering that has come to pervade local politics has in more subtle ways led to a much larger distortion in Congress.
According to a February Rolling Stone article, How Trump's Agenda Clashes With What Americans Want, the Republicans hold a majority in Congress despite being a full 23 million votes behind their Democratic challengers.
Given Congress's dithering over what to do about Trump, one might feel pessimistic that the people who have benefited from such distortions would seek in any way to remedy them. Nevertheless, the damage to America's image on the world stage is profound and dangerous. All of this is obvious and in plain sight. Thanks, Prof. Trump.
Lesson No. 3: Style vs. substance
Trump has shown that financial success, albeit tainted in his case, does not necessarily prepare a person for the high office of the presidency.
Matters of character are now overshadowed by those of style. In Trump's case, skills at making empty promises and mocking others were honed by his side career in television.
The two major parties were unable to present their array of alternate candidates to Trump in a forum that allowed the crucial distinction of substance as opposed to style to emerge. Trump has taught us, therefore, that clearly both parties need to scrutinize the processes and standards that underlie how they choose their presidential nominees.
New standards for primaries should be enforced by regulations and even laws if deemed necessary.
Clearly, too, the American public must become aware that the political realm is far more serious - and also duller - than flashy reality TV shows.
Lesson No. 4: Medical fitness to lead
Trump's rhetoric is essentially monotonous, consisting as it does of broad, grandiose promises, fiery denunciations and denials and petty mocking of those he sees as his inferiors, which is almost everyone. But he has taught us that he might not be well.
His secretary of state, Rex Tillerson, reportedly referred to him as a "moron". This is unfair and probably inaccurate. Two of my colleagues, both conversant with linguistic pathologies, believe Trump may exhibit signs of a progressive dementia.
The danger signs were apparently first noted by French translators. They found translating his utterances to be hard, if not impossible, because much of what he said was empty of referents and syntactically garbled or incomplete. In other words, Trump has limited tone of delivery, limited vocabulary, trouble finding the right word or finding the wrong one (bombing "Iraq" instead of Syria) and simple and incomplete sentence patterns.
Does Trump have some form of dementia? This question stands quite apart from the issue of political orientation, if Trump truly possesses a partisan bent at all. If he does have a dementia, then matters will only grow worse, not better.
Diagnoses from a distance are hard. What Trump has taught us, however, is that medical screening of a candidate cannot be a simple letter from a doctor saying that the candidate seems in good health, as was the case with Trump's questionable physician. A medical screening must be thorough and mandated by law.
Lesson No. 5: "Fake news" origins in Russia
Finally, and perhaps oddly, Trump has offered us many lessons on Russia, from its language to its hacking techniques.
Trump's biggest pet peeve is the media. The term "fake news" is uttered almost daily by Trump in reference to any story that is not fawning.
Due to my experience with Russia and the Caucasus, Trump's use of "fake news" was nagging at me. And like the last piece of a jigsaw puzzle, the obvious source recently struck me and shone a spotlight on the entire Trump presidency.
"Fake news" is a simple translation of the Russian phrase pod-del'nie novosti, "counterfeit or fake news" - literally "news (novosti) made (del'nie) underneath, in hiding (pod-)." The concept is a core one in Russian governance and has a long standing.
It has two basic senses. One is for domestic consumption, more or less propaganda, and serves to package any antagonistic event between Russia and another state as aggression against Russia, and any action on Russia's part as defensive.
The second sense means to plant false and provocative reports in other countries' media so as to sow social unrest, thereby weakening that nation. We now know that Russia has utilised social media both within the U.S. and across Europe to exacerbate inherent tensions.
In effect, Russia has jerked America around like a puppet on strings. Americans therefore, regardless of their political orientation, must acquire a sense of autonomy and integrity regarding the provocations that float across the internet from suspect news services.
What is most chilling, however, is that Trump himself promotes fake news. He is simply and openly pursuing Russian ends by Russian means. Why?
In part, his outbursts hide problems within his own circle. His ongoing attack on the NFL started the same day that we learned his inner circle were using private e-mail servers.
The pattern also seems to suit his peevish temperament. His attack on mayor Yulin Cruz of San Juan, Puerto Rico, for example, seems to have been a matter of merely venting his biases and disdainful attitudes, a feature of his narcissism.
Still, those outbursts also fulfil Russia's goal to weaken and divide the United States.
And if Trump does not find a way to sabotage the Robert Mueller investigation into his Russian ties, the special investigator will likely produce a wealth of evidence that threatens Trump's interests and even his tenure in office.
In conclusion, Trump's presidency has been a disaster for conservatives and liberals alike.
He has caused major damage both domestically and internationally, in the latter case to America's stature and reputation.
We should be grateful, however, because he has at least shown us the remarkable power of a new form of conflict, for the West at least - that of a modern media assault on the institutions and social fabric of our democracies by a clever and determined adversary.
The US military is already trying to contain Trump, with varying success. Congress must now show its true role as protector of the Republic and all it stands for and bring in articles of impeachment against Trump now before he can do yet more damage.
As Trump has taught us repeatedly, all of this is in plain sight.
John Colarusso is a Professor of Languages and Linguistics and Anthropology, Department of Anthropology, McMaster University, Canada.