EVERYONE knows by now that "Klara and Edda Belly Dancing" is a photograph by Nan Goldin of two little girls.

One of the girls is skimpily dressed and she is pictured standing over the other girl who lies on her back exposing fully her private parts.

The picture was seized by Northumbria Police from the Baltic Centre for Contemporary Art in Newcastle while on loan from Elton John. He thinks there is nothing obscene or objectionable about this picture and says on his website that it has been published around the world without any objections of which he is aware and auctioned twice by Sotheby's. So does that make it all right then?

Suppose you accidentally clicked on a pornographic website and saw a similar picture of a young girl exposing herself.

If you were challenged by the police, you would have to prove that you had come across the picture by accident and that you would never knowingly download such material. If you were not able satisfactorily to convince the police, you would be charged with viewing child pornography and punished accordingly.

So why is an almost exactly similar image judged acceptable in one context and criminally unacceptable in another?

The answer lies in that much misused word "art." I took pictures of all four of my kids in their bath when they were toddlers - not emphasising their private parts. And I never pretended that these charming little snaps were art. But modern art is generally so debased that there is now a fashion for a work of art to be anything anyone says is a work of art: an unmade bed, for example; or a light bulb flashing on and off. Nan Goldin took that picture of the girls, called it "art" and sold it for £3000. Barmy.

It's all a sham. Suppose I downloaded from a pornographic website an almost exactly similar picture of a girl displaying her private parts, printed it out, enlarged it and stuck it up on the wall over the piano. Suppose then I invited the police to come and look at it. They'd lock me up - and rightly. People who take pleasure in looking at obscene pictures of children ought to be locked up as a matter of course.

But absurdity is added to absurdity. If I took my camera to my grandson's school and tried to take a picture of him (fully clothed) as a shepherd in the nativity play, I would be prevented from doing so by the teachers - in case the photo fell into the hands of a paedophile. So it's alleged to be admirable to display an obscene picture of a child - so long as you call it art - but unacceptable to take an innocent photo of a school play! This is the world gone mad.

All through this article I have referred to the offending aspect of Goldin's picture as "private parts." And that is correct.

We need to recover the distinction between the public realm and what is private. And we should not be afraid to say that a thing is obscene when it is. Don't be cowed by the arty types and the pornographers into thinking that to protest against obscenity is to be a fuddy-duddy or an old puritan. There is no doubting that some things are obscene.

The ancient Greeks knew this and so, when there was a particularly bloody or lewd moment in the action of the drama, they didn't show it. They encouraged the audience to imagine the act taking place offstage. That's the very meaning of the world "obscene".

Some things simply shouldn't be seen.