Philip Kaufman's "Henry & June" is daringly, heroically sexy. Its subject is the relationship between the American writer Henry Miller (Fred Ward) and his wife, June (Uma Thurman), and their friend and lover, Anais Nin (Maria de Medeiros), in the Paris of the '30s. But beyond that, the film is about sex itself, and it's bold in the sense that, like Kaufman's previous film, "The Unbearable Lightness of Being," it expresses its themes of liberation and the quest for identity in erotic terms, seriously and uncompromisingly and for adults.

"Henry & June" isn't on an equal footing with that earlier film; it doesn't have the political scope or emotional comprehensiveness. But it is scintillating and deft and has the same quality of searching. The filmmaker and his wife, Rose, who together wrote the script, are engaged in a quest of their own. In defining their characters' struggles they define their own.

Nothing, these days, could be more sublimely anarchronistic. Watching "Henry & June," what you see is a conception of the cinema so rare that it seems almost to have vanished from the scene. Imagine, a movie that is sincere in its themes and its provocations, that is strikingly personal and concerns itself unabashedly with ideas and their expression.

To explore his subject, Kaufman creates his own bohemian universe, from the ground up, and we enter it through the character of Anais Nin, who as the film opens is attempting to find a publisher for her book on D.H. Lawrence. It's 1931, and the notion of a woman speaking out frankly on the subject of sex is a revolutionary one. In Miller, though, she sees a co-conspirator and kindred spirit. Unlike her devoted banker husband, Hugo (Richard E. Grant), Miller is an artist, but not of the sort she's used to. Penniless and unpublished, he talks like a boxer, in a street-tough Brooklyn accent. He frequents brothels and bums money openly on the streets. At their first lunch they're served a souffle, and, looking down at it, he says, "What's this?" and proceeds to take the whole top for himself.

Kaufman is the most Jungian of directors; he sees everything in terms of masculine and feminine forces, of anima and animus. In this sense, de Medeiros's Nin, with her gigantic, luminous eyes, is an ethereal spirit, more soul than flesh, and Miller, the fountain of pure masculine simplicity, the life force. But Nin is not all soul. Her flesh insistently calls to her, and in the night, in bed next to her husband, she feverishly scribbles down her wanton fantasies in her diary.

The arrival of June from New York adds another spirit to the mix, one of androgynous, opiated hedonism. June is all overheated emotionalism; with her heaving bosom, she is the earth mother. June wants to be chronicled, paid homage to (both Miller and Nin wrote about her their entire lives), but she makes a cranky, demanding muse. Reading over Miller's pages on her for what would become "Tropic of Cancer," she erupts with wounded fury and disappointment. "This is what I sacrificed for?" she says. "I wanted Dostoevski!"

Although eventually Nin becomes Miller's lover, it's June who inflames her most fervent dreams. At one point, she even goes as far as to have her husband pretend to make love to June while he is making love to her. The tone of these scenes is muscular, but never prurient. These people are obsessed with sex; they write about it, live it, and see themselves as adventurers, claiming an untamed, uncharted wilderness, and helping to reshape literature in the process. Kaufman doesn't dodge the material. Instead, he and his brilliant cinematographer, Philippe Rousselot, eroticize everything in the frame. The film is gorgeously crafted; its rhythms are mellifluous and its surfaces seductive.

Kaufman pulls enthralling performances from his main trio of actors, just as he did in "The Unbearable Lightness." De Medeiros's eyes are the soulful heart of "Henry & June." A newcomer to film from the French theater, she brings a tremulous urgency to Nin's explorations, and we sense in her the danger she feels in unburdening herself of her bourgeois conventionality. As Miller, Ward gives a hilarious rendition of burly American bravado, but he keeps the character's vulgarities in balance with his artistic drives. This is a star performance with a character actor's authenticity. It's a driving, impassioned piece of comic acting.

Thurman is the wild card; this is a nutty performance, but a great one, I think. June is a manipulator who plays her hand too boldly but never makes apologies, and as Thurman plays her, she's grandiosely carnal. At times her head seems so full of sex that she's about to topple over, and her tantrums are full-bodied. There's blood in her agonies. You can see why these artists are obsessed with her.

In terms of narrative, the movie wobbles a bit itself, but Kaufman has never been a tidy storyteller, and his discursions don't intrude on the film's momentum. What interests him most are the details of this period of artistic explosion in Paris, the circus atmosphere of dinner parties and trysts, where lovers quarrel and drink red wine and read each other's manuscripts. There's a marvelous section in which Kaufman's camera follows the photographer Brassai as he makes his rounds of the bars and nighttime haunts of the Paris demimonde. And what he captures is the thrill of that youthful time, when artists attempted to explode their boundaries.

What you sense in him, too, is a sense of nostalgia for that age, almost envy. He knew Nin (when he was young, she encouraged him to make movies), and he identifies with these boho fanatics, just as he did with the astronauts in "The Right Stuff" and the protesters during the Prague Spring in "The Unbearable Lightness." His nostalgia also extends to another age in filmmaking, and in both this film and his last one he seems almost to have remade himself in the image of an old European master. It seems nearly impossible, watching "Henry & June," that this is the work of an American. As a result, an odd, slightly distanced tone seeps into the movie, almost as if the director were working in a foreign language. Only this keeps "Henry & June" from being a great movie. But in no way does it hold it back from being a beautiful, captivating and spectacularly uninhibited one.

Henry & June, at area theaters, is rated NC-17 and contains adult material.