Zen Buddhism, as practitioners and theological scholars will be aware, is supposed to offer a path to inner enlightenment through mediation. Scholar Mei Yeung-Sheng (Lawrence Ng), the lead character in Michael Mak's Sex and Zen, appears to take a different view. For him enlightenment is something to be sought through copulation. Lots of it, and with as many women as possible. He makes this decision after visiting and disagreeing with a wise old sage known as the Cotton Sack Monk, so named for the cotton sack he carries with him wherever he goes. And the fact that he's a monk. His actual name is Lonely Hill, but that clarifies nothing. Cotton Sack warns Mei of the perils of adultery. It's all about karma. What goes around, comes around, that sort of thing. But our Mei is not to be dissuaded. Or is he? A very short while later, he marries the beautiful young Huk-Yeung (Amy Yip), and after a disastrous wedding night (she thinks sex is disgusting, he nearly cuts off his pecker with a knife), the two are at it like rabbits on aphrodisiacs.

Now this sort of arrangement would be enough for most men, especially given Huk-Yeung's captivating beauty and her new-found enthusiasm for just about any position she can get herself into, but not Scholar Mei. Accompanied by his unfortunate servant, he sets off on his original quest, to search for sexual enlightenment by seducing as many women as he can. It has to be said that his pick-up technique is not too sharp, and involves handing the target of his lust a book of explicitly erotic drawings and asking her if she dropped it. What a charmer. To assist him in his conquests he enlists the help of Choi Kunlun (Lo Lieh), the famous Flying Thief. Oh come on, you must have heard of him. After first robbing Mei and then paying him back with interest, Choi agrees to help, but on discovering that this would-be ladykiller is short on stamina and equipped with a toothpick-sized penis, he opts out of the deal. Mei would have to be hung like a horse before Choi would get involved in such a venture. Can you see where this is heading? If you're thinking in terms of realistic plots and characters, probably not. For Mei, there's only one solution. Chance lands him in the care of heavy drinking Doctor Tin Chan (Kent Cheng), a man skilled in repairing injured limbs who has been studying the process of transplanting an animal penis onto a human. Now can you see where this is heading? Mei wants a horse's dick and Chan is the man to supply him with one.

Now I should point out that we've reached this stage in the busy and fast-paced narrative via quite a bit of sex, all of it softcore but some of it bordering on a stronger classification, notably Huk-Yeung's creative approach to calligraphy (it's not what she writes, but how she holds the brush) and an eye-popping sequence involving two women and a flute. But it's also played for laughs. Mei's wedding night in particular is a catalogue of misadventures, and he only ends up at Chan's place after attempting to cut off his undersized member and accidentally stabbing his servant in the crotch. Checking the damage, it's not the wound he has inflicted that horrifies him but the realisation that even his lowly servant is better endowed than he is.

But in the transplant scene the film throws all caution to the dogs and is almost transformed into Carry on Cockswap as directed by Farrelly Brothers. Taste is not an issue and there are moments here seemingly designed to prompt male viewers to cross their legs and clamp their mouths shut in horror. From here on in reality takes a seat in another room, as Mei puts his ludicrously oversized appendage to use, delivering new levels to pleasure to women who by some miracle escape suffering organ damage and having their teeth dislodged.

Sex and Zen was adapted from Li Yu's notorious novel The Carnal Prayer Mat (the original Chinese title of this film, Rou pu tuan zhi tou qing bao jian, refers to the book and the adapted story, or so a Chinese friend assures me), which was written some time during the Ming Dynasty and banned in China for 400 years. On the surface, it's a celebration of sex at its most energetic and adventurous, a frequently and enthusiastically enjoyed activity whose practitioners employ everything from stirrups and chains to ladders and whips. Food is also part of the mix, borrowing a memorable snacking scene from Ai no Corrida and using bread in a way that might put you off sandwiches for life. It's softcore porn with a risqué edge, but done with humour, imagination and a little bit of class. The girls are hot, even the guys look good (well, most of them), and the photography and set dressing are often gorgeous, easily the equal of the most polished mainstream period piece.

And yet...

Sex and Zen has plenty of cake, but it wants to eat it too, and leaves us with the message (if you're planning to watch the film primarily for its plot – yeah, right – then you might want to skip this paragraph) that the Cotton Sack Monk was right after all and that all these sexual adventures lead only to disaster and suffering. A film that trades on its erotic content and whose principal raison d'être is to sexually excite the viewer turns out to be pro-monogamy and even celibacy. After showing us how much fun sex can be, it then suggests that this way lies ruin. Although this does make for a more dramatically interesting ending, it's unlikely to cut too much ice with those who have been drooling over the earlier adventures.

A bigger problem for many, myself included, will be the textile shop owner and his treatment of his wife. Set up as the film's bad guy and a crucial cog in the mechanism that brings the narrative to such a moral conclusion, he is first observed by Mei, Choi and us losing his rag with his better half and then raping her. The scene has dramatic purpose, sure, but is presented as an erotic, slightly comic spectacle in the same manner as other such set-pieces, with little concern for the context in which it is taking place. It's a memorable sequence, but for all the wrong reasons. And I can't be the only one who, even in the context of a light-hearted sex film, has trouble with the suggestion that what this abused wife really wants when her husband is away is to be seduced by a man with a three-foot long horse cock.

One of Hong Kong Legends' Ultrabit titles, Sex and Zen justifies the banner. A sharp transfer with terrific colour rendition and contrast and hardly a dust mark or compression artefact in sight, it really does justice to Hung Poon Hung Poon's lush cinematography. Occasionally it feels as if the brightness is up a bit, but never to the transfer's detriment. The framing is 1.85:1 and the picture is anamorphically enhanced.

The original Chinese mono is included and it's rather good, but the 5.1 remix is nicer, better serving the music, dialogue and sound effects. The surrounds aren't very active, but the clarity and quality still give it the edge over the mono track. The front separation is distinct in places. The 5.1 American English dub isn't that bad as these things go.

No commentary? I'm not exactly surprised, although it amuses me to imagine what it would have consisted of and how it would have been delivered. No, it's an Ultrabit disc, so all we get is A Lot of Sex, A Little Zen, a detailed essay on the film from the Stefan Hammond, co-author of Sex and Zen and a Bullet in the Head – the Essential Guide to Hong Kong's Mind-bending Films. The first half of plot is outlined in considerable detail, so save this one for afterwards.

Sex and Zen is, for the most part, a film that lives up to its steamy reputation, and is erotic and fun and a little bit outrageous. The conflict between message and delivery doesn't really harm the film, but I'm still not happy about that scene with the textile shop owner and his wife, an ugly grub in an otherwise rather nice ointment. Once again this Hong Kong Legends Ultrabit disc is an extra features wasteland, but the transfer is lovely enough to keep fans of the film happy.