In some countries, the head of state — say, the Queen of England — is not the same job as head of the government, which in Great Britain is the prime minister. The Queen — always capitalized — is the symbol of the nation, above day-to-day politics, but the elected prime minister is the operational head of the state.

It is the fate of American presidents to have to combine the two roles. Sometimes that’s difficult, and sometimes it is a dual role that can be misused. President Richard Nixon appealed for loyalty to the presidency to avoid punishment for his crimes, for example.

On some days, solemnity makes the dual role much easier. The appearances of Presidents Barack Obama and George W. Bush at ceremonies making the 9/11 terrorist attacks helped to reinforce the idea that Americans have more in common than not.

For the president on duty when terrorists struck on Sept. 11, 2001, the ceremonies of remembrance marked a victory of sorts, al-though the actual raid on Osama bin Laden’s hideout in Pakistan occurred on the watch of his successor.

The nation is best served by presidents who, however intense the political battles of the time, remember that they should seek to unify the nation, and represent the best intentions of the American people.