Somehow, the accent makes all the difference. The murderer in the Islamic State videos speaks “Jafaican,” a street cant that young people from different ethnic backgrounds across southern England have picked up. I’m not sure what the closest American equivalent would be: Perhaps the painful way in which some white boys try to talk like rappers. In any event, Jihadi John’s dialect serves to emphasize the emptiness and vanity of his message. When we see hooded Islamists talking in musical, aspirated Arabic, we assume that something is being lost in translation. But self-regarding diatribes in this debased patois irresistibly recall Hannah Arendt’s phrase, “the banality of evil”.

What attracts boys from comfortable Western homes to such evil? Is it something in their religion, something in their socio-economic circumstances or something in their character?