Today a page turns in the chronicle of American history, as Donald J. Trump takes the oath of office to become the 45th president of the United States. Thus begins a new era for the country, one likely to be transformative. Whether that's in a positive or negative way will depend in large part on the mindset, choices and actions of the new man in the Oval Office.

While the president is not the country’s sole leader — under the Constitution, the executive is on equal footing with the legislative and judicial branches — the presidency’s import and influence can scarcely be overstated. The president exercises executive authority, choosing how laws will be enforced and exercising veto power on legislation. He serves as commander in chief of the country’s armed forces. He sets our foreign policy, with diplomats such as the secretary of state expected to work toward his goals. He serves a symbolic function as head of state, a symbol of the continuity of our form of government.

And, more than anything else, the president sets the tone for the nation — for how we’ll relate to other nations, yes, but also how we’ll relate to one another: What is the country’s public discourse going to sound like; what will be our view of ourselves? Whether we like it or not, we take our cue from the president.

So as Trump takes office today, he can resolve to set a powerfully positive tone for the nation. He can choose to work for policies that will better the lives of all Americans. He can look to the examples, good and bad, of his 43 predecessors (Grover Cleveland, with his nonconsecutive terms, counts twice), to realize the important qualities a president must have:

The president must be wise. He must collect information from a variety of sources, including input from intelligence agencies, advice from cabinet members and the informed views of the American people (as expressed in polls, through the media or in direct correspondence). He can’t afford to be strictly partisan in considering sources, either. The president must weigh the credibility of this information and carefully consider the potential outcomes of the various ways he might act on it. This can’t be done in a moment’s decision or a gut reaction. It requires an ability to reflect, to appreciate ramifications of actions, and determine what ramifications we can live with.

The president must be decisive while maintaining a certain flexibility. The populace, as well as Congress, as well as our allies abroad, must be able to know with confidence that the president’s overall approach to policy will be consistent. That said, he needs to be able to alter and tweak policy approaches when he has received and processed new information. Still, the president needs to clearly communicate his policy approaches, in as much detail as possible.

The president must be inclusive in working for policies for the good of all Americans, in terms of public health, public safety and protection of civil rights. That’s all Americans, of all classes, races, religions (or none), genders and gender expressions, and political affiliations. A president can’t afford thinking of any Americans as enemies or losers — just as “my fellow Americans” whose benefit he seeks.

The president must be disciplined. He cannot afford the luxury of a hot temper, of taking offense at slights and satire and criticism, of instantly responding to critics with anger or ridicule. A president’s approach to criticism should be to carefully consider the points made, determine whether there is any truth to them — and if there is, consider making a change. (And if there isn’t, simply ignore it — a president’s skin must be thick as a rhino’s.) That’s really how we all should respond to criticism, but it’s especially important for one with the power and station of the president.

Which leads to an ironic point for such a powerful position: A president must be humble. He must realize the limits of the office’s powers, and his own limitations as a human. He must beware the temptation of a lone-wolf approach, of thinking he knows it all or best, and doesn’t need the input of, say, Congress or critics in his party or the opposition party for that matter. He must know that he cannot speak the world he wants into being — that he can’t always get what he wants. And to still do his best for the American people.

Finally, a president should inspire. As the symbolic head of state, he has the ability to move Americans to, for instance, ask not what their country can for them but rather what they can do for their country; to fear nothing but fear itself; to be a kinder, gentler nation; to proceed with malice toward none and charity for all. Not every chief executive is gifted with eloquence, but one need not have a golden tongue to appeal, as did a plain-spoken lawyer named Lincoln, to “the better angels of our nature.”

We wish President Trump well as he assumes his responsibilities today. If he internalizes and maintains these attributes, his presidency stands a good chance of being successful — for himself, and for the United States. May his "better angels" prevail.