No ordinary Joe

In 2011, Danish bad boy Lars von Trier travelled to the Cannes Film Festival to unveil his latest provocation, Melancholia, with his starry cast, including Charlotte Gainsbourg, Kirsten Dunst, John Hurt and Stellan Skarsgard, in tow.

During a press conference, von Trier was asked about his German roots and how it connected to his taste for the Gothic and his interest in "the nazi aesthetic".

"The only thing I can say about that is that I thought I was a Jew for a long time and was very happy being a Jew. But then I found out I was really a nazi because my family was German which also gave me some pleasure," von Trier replied.

"What can I say? I understand Hitler. I think he did some wrong things, absolutely, but I can see him sitting in his bunker in the end. I think I understand the man and I sympathise with him a little bit."

Realising he'd dug himself into a hole too deep to get out of, von Trier went for broke and blurted out "Okay, I'm a nazi", leaving his French leading lady Gainsbourg chuckling and the Hollywood star Dunst looking mortified.

Journalists in the room laughed nervously at yet another piece of calculated von Trier outrage (he once referred to jury president Roman Polanski as "the dwarf" when one of his earlier films missed out on the Palme d'Or).

But once the nazi comments bounced around Cannes and the rest of the world, von Trier was pilloried, forcing the festival board to declare him persona non grata.

Von Trier apologised in his own inimitable way, boasting that he was proud to be persona non grata, accusing the French of overreacting because of their own appalling treatment of Jews during World War II and arguing that international journalists didn't understand the Danish sense of humour.

But the incident clearly stung von Trier who said he would no longer speak to the media or make public statements, which is why in promoting his latest movie he released the image of himself with his mouth taped shut.

Of course, von Trier is no nazi. He may be insensitive, undiplomatic or, in reference to his 1998 film about a group of Danes who pretend to be mentally disabled to provoke a response from the bourgeoisie, a bit of an idiot.

But anyone familiar with the von Trier oeuvre, from his early highly stylised thrillers Element of Crime (1984) and Zentropa (1991), through to his post-Dogma explorations The Idiots and Dancer in the Dark (1998), the Brechtian dissections of the American politics and society Dogville (2003) and Manderlay (2005), can see that von Trier is an old-fashioned European cultural radical in the tradition of Luis Bunuel, Pier Paolo Pasolini and Dusan Makavejev.

For him good taste and middle-class values are a form of fascism that he will employ any means to challenge, which includes using his production facility outside Copenhagen to produce hardcore pornographic movies (his company Zentropa is the first mainstream production house to get involved in the porn industry). He's ploughing the same turf as Pussy Riot's protests in Vladimir Putin's increasingly repressive Russia.

So rather than backing down and accepting an offer to work in Hollywood, the 57-year-old former Lars Trier - according to legend he added the "von" in homage to such grandiose Golden Age directors as Erich von Stroheim and Josef von Sternberg - has conjured up his most confronting and controversial film yet, a breathtakingly graphic two-part, four-hour sex epic titled Nymphomaniac.

Completing his so-called Depression Trilogy, following Antichrist (2009) and Melancholia (2011), von Trier tracks the erotic adventures of a sex addict named Joe across almost half a century, from her infantile discovery of her vagina and her years of discovery and experiment through to the later period of physical and emotional exhaustion, in which her genitals are literally raw through overuse.

I've never been a fan of von Trier's movies, apart from the odd highlight such as Zentropa and Dogville. I've found his work in his middle period such as Breaking the Waves (1996), Dancer in the Dark and the recent Melancholia too messy, too undisciplined, too much of an unexamined emotional eruption that gave his actresses great roles but left the audience drained, puzzled and annoyed.

However, I was so enthralled by Nymphomania, which I saw in two two-hour sessions on consecutive days that it has forced me to go back and reconsider the von Trier oeuvre and even take his prankish public statements more seriously. Or not.

After looking back at the "I'm a nazi" crack and the swift denial followed by a "then again . . ." and now being swept away by Nymphomaniac I see that von Trier has matured into a first-rate dramatist in the purest sense, a dialectical thinker who sets up two extreme and opposite positions and invites the audiences to thrill to the clash of ideas.

Nymphomania is as graphic and as shocking as you have been suspecting since von Trier launched the film's ingenious marketing campaign with the multinational cast - Gainsbourg (the adult Joe), Stacey Martin (the young Joe), Shia LaBeouf, Skarsgard, Willem Dafoe, Uma Thurman and Jamie Bell - featured on individual posters showing themselves in orgasmic thrall.

What holds this surprisingly funny picaresque adventure together is the framing device of Gainsbourg's Joe recounting her story to gentlemanly asexual scholar Seligman (Skarsgard) after he finds her bruised and beaten in the wake of what we presume was another dispiriting anonymous tryst.

However, rather than just listening, Seligman challenges her at every turn, countering that she's not "a bad human being" because of her voracious sexual appetite. "If you were a man nobody would be interested in your story," he reassures her.

It then evolves into the most fascinating and probing examination of female sexuality in memory as the sympathetic Seligman uses a dizzying array of cultural and historical references to account for her behaviour, ranging from the Fibonacci sequence, Bach's choral works and the Bible, and Joe countering with even more toe-curling stories, culminating in her Fifty Shades of Grey-style S&M relationship with a cold-blooded sex therapist (Jamie Bell).

This beautifully acted framing device adds a dimension to Nymphomaniac I've not encountered in a von Trier movie, with every sexual encounter filtered through incendiary ideas and overlaid with the "Danish sense of humour" - so much so you are never sure if Joe's stories are real or imagined or if the whole movie is a giant joke, despite the filmmaking being of the highest order.

As Larry Gross writes: "Von Trier has become a Nabokovian invention, fostering the image of himself as a fraudulent wannabe, when - wonder of wonders - he's the real deal. Most of us mediocrities want to be taken seriously. Von Trier, who's made more great or near-great films than any European director under 60 except Almodovar, does a perfect imitation of a fake."