"Antisemitism is a menace. It is not simply the preserve of knuckle-dragging neo-Nazi skinheads; this centuries-old sickness infects progressive circles, too. There are people reading this and thinking "ah, but what about Israel?" I know this because whenever I tweet about antisemitism, someone replies with a sentence along those lines. Sorry to sound self-righteous here, but if that's you, then you're part of the problem."