WHERE do I start? Perhaps with the viral image that will come to define this episode: a child who'd be three or four hoisting a sign triumphantly above his head blaring ''Behead all those who insult the Prophet'' while a woman, presumably his mother, thinks this is cute enough to capture on her smartphone. Alternatively, I could begin with the observation that the trailer for the anti-Islamic film that ostensibly started this all, Innocence of Muslims, is now a blockbuster, with YouTube hits in the millions thanks largely to the protesters around the world who think nobody should see it.

No. Let's start with the fact that so few of the protesters who descended on Sydney's CBD this weekend seem actually to have seen the film that so gravely offends them. When asked by journalists, they bluntly admit this, one even adding that she refuses to watch something so offensive. It's almost impressive how cyclical this stupidity is. But it's also instructive. In fact, this is the key to making sense of something so gobsmackingly senseless. The protesters - at least the ones quoted in news reports - know nothing except how offended they are.

That, you see, is all that matters. This isn't about a film. It's about an excuse. We know because we've seen it all before, like when Pakistani protesters vandalised American fast food outlets and burnt effigies of President George W. Bush in response to the Danish cartoons.