It’s often observed that no one is prepared to be president, that every president must grow into the job. Donald Trump arguably enters the job from further back on the learning curve than any of his predecessors. He is the first president never to have served in any part of government, including the military. That’s a big element of his appeal to millions of supporters who are fed up with politicians and the world they’ve created. Trump is an outsider, not even one of those CEOs who like to visit Washington, influencing policy. As a businessman, however, his abilities and successes were as a dealmaker, not as a leader; visitors to the Trump Organization’s headquarters in Trump Tower are always surprised at how few people comprise his corporate staff.

So Trump takes charge of governing the world’s most powerful nation and largest economy with no government experience and slim credentials as a leader—not a promising résumé. But remember, no one is ever prepared. So what should we expect? The best insights I’ve seen come from two seasoned presidential historians, Richard Reeves and Doris Kearns Goodwin.

In a book about John F. Kennedy as president, Reeves wrote, “He was not prepared for it, but I doubt that anyone ever was or ever will be. The job is sui generis. The presidency is an act of faith.” Reeves debunks most people’s expectations of a president by identifying what he says is the most important fact about being president. It’s this: “The toughest job in the world is essentially reactive. The president does not run the country and is not paid by the hour. He is there to respond to events unanticipated.”

History supports his view; think of Obama taking charge at the depth of the last recession, or Bush 43 responding to 9/11. Reeves notes, “Presidents are alone, facing the unknown. The job … is about leading the nation in unexpected crisis or danger. No one remembers whether Lincoln balanced the budget.”

Goodwin, speaking on Tuesday in Michigan, mused on Trump’s insistence that he is always a winner; his ultimate insult seems to be “loser.” Yet she noted that Lincoln suffered from debilitating depression and endured multiple political defeats. Franklin Roosevelt was crippled by polio. From those experiences of loss they “learned patience and resilience.”

She is encouraged that several of Trump’s cabinet nominees are expressing views contrary to his in their confirmation hearings; conflicting views often lead to better decisions. Still uncertain is whether Trump fully knew of their views when he appointed them. Goodwin also offered a bit of advice from Lincoln, who often wrote “hot letters” to those who made him angry, but never sent them. Maybe Trump could set up a pretend Twitter account.

Reeves wrote in 2008, “No one knows what will be the issue that defines the next president.” That is always true; what makes this presidency one of the largest experiments in our history is that, more than in living memory, and regardless of what that defining issue may be, we have almost no idea how the new commander in chief will respond. Even more than past presidencies, this one is an act of faith.

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