"What do we not yet know about Donald Trump?"

“We have known since nearly the beginning of Donald Trump’s presidency that he believes his first attorney general was a dangerous idiot. We have known for nearly as long that his first secretaries of state and defense think the same thing about Trump.

“We know, because Bob Woodward told us in a book two years ago, that some advisers are so anxious that the president could do something impulsive or boneheaded that they skulk into the Oval Office to take papers off his desk. We know, because former national security adviser John Bolton told us this month in a book of his own, that Trump allegedly shreds ethical lines between the nation’s foreign policy and his personal considerations, proposing crude bargains with the dictator of China to help his reelection or trying to help the dictator of Turkey to shut down a bothersome criminal case.

“We know that the president lives in a state of agitated grievance, spending countless dark hours when most people are sleeping fulminating against his enemies and bemoaning that he is being insufficiently praised. We know this, of course, because Trump compulsively narrates his own thought stream in real time on Twitter.

Three and a half years into his presidency we know so much that it raises the question: What do we not yet know about Donald Trump?... It's as though Trump has turned history itself into an amphetamine addict—disoriented and sleep-deprived, craving more stimulation, no longer able to get high off standard dosages…

“Here are a half-dozen Trump bombshells that have yet to go off—but almost certainly will someday…

“The business of the presidency/the presidency of the business: Historians reconstructing the Trump years will need to work long and deep to understand ‘the unprecedented nature of a business presidency,’ said Jonathan Karp, chief executive officer of Simon & Schuster, who edited the memoirs of Senate legends Edward M. Kennedy and John McCain.

“Unfortunately, those writers will get less of a head start from daily journalism than ideally would be the case. Trump was elected president on the strength of his self-proclaimed business mastery. But he reneged on his 2016 pledge to release his taxes, as every presidential nominee in the modern era has done. The New York Times has done landmark projects on the Trump family’s tax history, and the president’s long and complex relationship with Deutsche Bank.

“But questions swirl about the exact size of Trump’s fortune and whether the reality matches Trump’s claims; the nature of the family’s past and current business dealings overseas; the extent to which foreign interests seek to influence Trump through favorable dealings with his holdings or those of family members; the degree to which his hotels and other business operations have reaped enhanced revenue because of Trump’s presidency. For historical context, consider that Bill Clinton was investigated by an independent prosecutor for most of his presidency over comparatively small business dealings that took place a decade or more before he came to Washington…

“The Russia mystery: Prosecutor Robert Mueller could not prove a criminal conspiracy in which Trump colluded with Russia to affect the election. But that conclusion does not mean that questions about Russia’s role in Trump’s election or presidency are ‘a hoax,’ as Trump often says.

“It is ‘not a hoax,’ but a critical line of inquiry to understand the president’s relationship with Russian leader Vladimir Putin, said Peter Baker, a New York Times White House reporter who has written books dealing extensively with the Clinton, Obama, and both Bush presidencies.

“Someday, just as happened with Moscow’s view of the Cuban Missile Crisis, there will be Russian documents and Russian officials to help explain why Russia promoted email break-ins and social media propaganda to help Trump over Hillary Clinton in 2016. Or, once elected, why Trump kicked out U.S. official note takers in a meeting with Putin. ‘We don’t have the explanation why’ on multiple questions, Baker said, in an interview. ‘Why is Trump so seemingly enamored of Putin? He so desperately wants his approval.’

“The real inner circle: On different occasions, people close to Trump in an official sense have been described in books or journalistic accounts referring to their boss as an ‘idiot’ (former chief of staff John Kelly and former national security adviser H.R. McMaster), a ‘moron,’ (former secretary of state Rex Tillerson), ‘like an 11-year-old child’ (former aide Steve Bannon) with an understanding of world affairs akin to ‘a fifth- or sixth-grader’ (former defense secretary James Mattis).

“But here’s who you have not heard spilling secrets about Trump: Ex-spouses, or children, or other people who love Trump or once loved him, or even people like household staff who had occasion to observe him in intimate settings.

“Washington Post writer Mary Jordan this month published ‘The Art of Her Deal,’ on Melania Trump. The book came with a noteworthy scoop: That the first lady had renegotiated her prenuptial agreement with the president after his election.

“But the book also underscored how little is understood about Trump’s most personal relationships and their dynamics, and what Trump is genuinely like when he’s not on television or Twitter. We know that Ivanka Trump and Jared Kusher are influential, of course, but have insight into barely a fraction of their interactions with the president.

“Jordan told me she was struck by how much time Trump spends alone, up late or early, without ‘real friends.’ The relationships he does have are often shielded by a wave of nondisclosure agreements or other financial or legal incentives. Jordan recalled once approaching someone who had been around Trump in family settings and the person ‘was shaking like a leaf’ for fear that he would be punished for being a source.

“Silence rarely lasts forever, especially once a president is out of office or is deceased, and these recollections promise to be a rich vein for understanding a president who is startlingly transparent about some aspects of his psychology and unnervingly opaque about others.

“When the documents speak: The modern presidency keeps a lot of records, which is why modern presidents have often worked hard to keep those records secret as long as possible. When they do open up, they tell stories. The journalist Richard Reeves used them from the Kennedy years to write a book reconstructing in sometimes minute-by-minute detail key days of JFK’s presidency.

“When supplemented with oral histories, or contemporaneous journals (some people still keep them) there are lots of stories the documents might tell even if Trump wishes they never get told. Who does Trump meet with and talk to on the phone? This might illuminate one of the major stories of the Trump years, which is the real relationships between an anti-establishment president with many establishment Republicans and corporate leaders who either publicly or privately profess to loathe him.

“What is the role of Vice President Mike Pence, who never conveys anything but unqualified support for Trump, and what can we learn about his real views and how he put them into practice? Did senior officials who have made clear they regard Trump as erratic ever take steps that we don’t currently know about to implement the 25th Amendment challenging his fitness for office?

“Have we come closer than is currently known to an impulsive military action? How much knowledge and active engagement does Trump have with daily functions of the executive branch that don’t get played up on cable news? Many key policy and regulatory jobs are held by conservatives who have strong views and wide latitude to act on them, whether or not the president is interested in the details.

“What is the real state of Trump’s health?: If Trump’s health is more troubled than usually terse official statements are letting on, he would not be the first president for whom this is the case. The physical and cognitive condition of presidents has been a key avenue of inquiry for historians of Woodrow Wilson, Franklin D. Roosevelt, John F. Kennedy, and Ronald Reagan.

“What was that unscheduled trip to Walter Reed Army Medical Center last November all about? What explains Trump’s unsteady appearance drinking water or walking down a ramp at West Point earlier this month?

“Reading the thought bubbles: ‘We will find out eventually all the things that they do, even their taxes,’ Jordan said of the Trumps. ‘The questions we don’t know the answer to are about what’s in their minds.’

“‘Does he have unexpressed thoughts?’ asked presidential historian Jon Meacham. The tendency to assume that Trump has no introspection or strategic sense beyond what he shares on Twitter may itself be too superficial, he added.

“In the world abroad, Meacham asked, what explains the tension between Trump’s blustery talk but seemingly dovish instincts on use of military force? Here at home, since his early New York days, Trump has been skilled at manipulating his image and penetrating establishment circles while remaining independent of them. Does he operate from a theory of power or on improvisational instinct alone?

“‘He’s so good at making us focus on the part of the iceberg we can see,’ Meacham said. ‘I’m not suggesting there are great hidden depths to him, but there is stuff we don’t know.’ And there are things about America during the Trump years, we don’t know. ‘I’m more interested in what he says about the country than what happened moment-to-moment in the Oval Office. His grip on 40 percent of us is fascinating.’

“Until the deeper dimensions of the Trump years are illuminated, his closer-to-the-surface ruminations are keeping the daily historians busy. ‘Imagine if the Nixon tapes were played every night on Walter Cronkite,’ Baker observed. ‘We are seeing all the stuff that is usually hidden play out in real time’” (The Six Trump Bombshells Still Waiting to Explode by John F. Harris, Politico).