It feels rude to point out how little was expected of Harry Truman when he became US president 75 Aprils ago. He was “just” a Missouri haberdasher. He is still the last non-graduate to attain the office. After Franklin Roosevelt, who matched Albert Einstein as the man of the 20th century, snobs viewed his instalment as an act of bathos.

Truman would end up curating the second half of that century. Nato was his doing, as was Bretton Woods, the Marshall Plan and the nuclear age. Perhaps a Napoleonic gift for command always lurked underneath that Everyman bonhomie. More likely, though, the world happened to be at its most pliable in 1945. Circumstances counted for more than the individual.

Joe Biden must look at the parable of Truman with indecent relish. A president is never more powerful than after an international crisis. With the world in flux, he need not be an obviously great man to be of great consequence. If the underwhelming Democrat beats President Donald Trump in November, he will have a globe- and era-shaping opportunity.