Liz Herring was a driven debater. At school, she carted around a metal box of index cards so she could swot up on topics between classes. A debate teammate told the New York Times: “She wanted to be the best. She wanted it more than I did. She wanted it more than anybody did.”

Herring grew up to be Elizabeth Warren, US senator and would-be president, fuelled by a “lust for success”, according to Barbara Kellerman. “Lust really separates most ordinary leaders?.?.?.?from the exceptional ones,” the Harvard Kennedy School leadership professor told me last week.

Presidential candidates and nominees are frequently lustful. Even apparently mild-mannered Joe Biden lusts for success, while Prof Kellerman believes Donald Trump is principally driven by desire for money.