Reporting on the trial of Adolf Eichmann in Jerusalem in 1961, the political theorist Hannah Arendt coined the phrase “the banality of evil”. Eichmann, responsible for the slaughter of millions of Jews, had the appearance and even the mentality of a petty bureaucrat or administrator, crunching numbers and logistics that could have concerned widgets but happened to involve the mass murder of human beings. The former employee of the Vacuum Oil Company was examined by a team of psychologists who pronounced him perfectly “normal” – “more normal at any rate than I am”, as one of them said with black humour, “after having examined him”.

When Arendt wrote, humanity was still reeling from the first total war in history, from the revelations of the Holocaust, the pitiful starvation of inmates at Belsen, the aftermath of the atomic bombs dropped on Hiroshima and Nagasaki. Evil loomed large and dramatic on the face of the planet, and it was something of a shock to find its incarnation in such commonplace, trite human beings as Eichmann and the thousands of others who were simply “obeying orders”.