On a sudden interest in Japanese art

"The Passionate Art of Utamaro", currently running at the British Museum, is proving to be one of the most successful exhibitions of oriental prints ever mounted there. It would be nice to be high-minded about the reasons for this - to assume that the attendance figures were simply a reflection of the strength of the tourist yen or an undetected public thirst for the delicate art of Ukiyo-e woodcut. But it seems a good bet that the show is drawing some Museum virgins, visitors attracted by the publicity's coquettish promise of sex in hushed galleries.

It may prove a disappointment to the lecherous - first of all because the small representation of Utamaro's pornographic prints is greatly outweighed by hundreds of more decorous pictures. Barring the odd glimpse of pale breasts, there are around 20 sexually explicit works in the exhibition, alongside hundreds that would not bring a blush to a Carmelite's cheek. Some of these, it's true, turn out to be erotically charged; they are representations of love or portraits of courtesans (possibly given away by brothels as promotional gifts for valued customers, possibly even used as advertisements). But any vicarious arousal would be a scholarly thing - to an untutored eye the portraits are virtually identical, an assemblage of facial components that vary only minutely from print to print. Extremes of emotion become almost undetectable in this highly coded world - a woman in the throes of love reveals the fact only through a droop of the head and a few stray wisps escaping from the honed curves of her hairstyle. It's true, too, that Utamaro's ability to render fabric - the weight and texture of cloth against skin - is extremely sensuous, but then sensuous is not quite what the average user of pornography is after.

Scholarship also makes it clear that some of the work is impure in motive. A beautiful series of six portraits, each with a woven straw basket in the background, turns out to be "The Peers of Sake likened to Select Denizens of Six Houses" - the baskets are actually sake barrels, each displaying the trademark of a famous producer. In other words they're promotional posters, the Lamb's Navy Rum girl transformed by art. In front of these exquisite pieces of hucksterism you offer up a silent prayer of thanks that photography had not been invented; these days, when a firm wants to add a gloss of refinement to their cheesecake, they hire Lord Lichfield.

But even the out-and-out pornography may not do the trick, though it is far more explicit than anything you could find on the top shelf of a local newsagent. Each plate shows a gnarled entanglement of genitalia, every fold and vein depicted with marvellous clarity. And while these images are arousing, they are so in an oddly intermittent way. The instincts of the body suffer from aesthetic interference, as though the titillating signal has been weakened by distance and time. Looking at these prints you keep being distracted by depiction, so that wonderment at the exactitude of the thing gets in the way of what those delicate lines trace.

Two sorts of lust are competing here - the appetites of the body and the hunger of the eye - and almost always it is the latter that wins. One of the few scroll paintings in the exhibition depicts a sexual assault - an older man groping a young woman, exposing her thighs and the pure curve of her vagina, downed with fine hair. But your gaze is constantly drawn away from that sexual focus to the surrounding folds of cloth, sumptuously patterned and coloured. There is nothing dispassionate about your inspection - it feels like a visual caress, and it blends very oddly with the pulse of other urges. Those with baser desires shouldn't be misled by that suggestive title, but if you have lascivious eyes don't miss the show.