America never knows for sure what it is going to get in its next president. It can look back and give thanks that George Washington won in 1789, Abraham Lincoln in 1860 and Franklin Delano Roosevelt in 1932, because history might have turned out differently if John Adams, John C. Breckenridge or Herbert Hoover had prevailed, though Mr Adams was to get his chance later and Mr Hoover already had his.

The more partisan would assign great weight to the victories of John F. Kennedy in 1960 and Ronald Reagan 20 years later. But accidental presidents have been consequential, too: Theodore Roosevelt, elevated by assassination; Harry Truman, by death and, briefly, Gerald Ford, by resignation. Even the disastrous, from James Buchanan to George W. Bush, left more than “a wrack behind”, to misquote Prospero in The Tempest (in the current case, more like a wreck).