Joe (Stacy Martin), right, tells a story of competing with her friend, B (Sophie Kennedy Clark), to seduce the most men on a moving train in “Nymphomaniac: Volume I.” (Christian Geisnaes)

Joe, the title character in Lars von Trier’s “Nymphomaniac: Volume I,” announces early in the movie that the source of her sexual compulsion isn’t so much physical or emotional as much as aesthetic: From a young age, she has been chasing an impossible sensory ideal, a pursuit that, judging by her battered, bloodied face, has gotten her into heaps of trouble.

“I always wanted more from a sunset,” Joe (Charlotte Gainsbourg) says at one point. The viewer of “Nymphomaniac” will know how she feels. Like so many von Trier enterprises, this film feels less than the sum of its parts, made by someone who, for all his mastery of the form, still struggles to find something genuinely deep and new to say. His films nearly always contain elements to value; we just want more.

Von Trier is a notorious cinematic “bad boy” and provocateur, a Barnum-esque showman who expertly manipulates outrage and taboos to make news and acolytes of actors eager to be pulled like taffy into his stark, often physically punishing visions. But it’s impossible to dismiss von Trier as merely a hype-monger. He’s too damnably good a filmmaker for that. Watching “Nymphomaniac” is to be reminded of his superb skills in creating vivid worlds and characters on screen.

Should filmgoers find themselves needing that ineffable more after “Nymphomaniac: Volume I,” their cravings may well be satisfied by “Volume II,” which is scheduled to be released in early April. For now, however, all we have is the first installment, which opens in a cold, snowy alley where Gainsbourg’s Joe is sprawled, unconscious, presumably after being attacked. She’s discovered by Seligman (Stellan Skarsgard), who takes her to his monastic home, puts her to bed with a cup of tea and listens to the story of her life. Her Proustian reverie and self-critical confession begins with her sexual awakening as a young girl and takes her through a defiantly promiscuous adolescence and more neurotically driven young adulthood.

In these flashbacks, Joe is played by newcomer Stacy Martin, a lovely young actress who, either by accident or design, projects a vague, breathy blankness that grows increasingly tiresome as “Nymphomaniac” proceeds. It doesn’t help that her opposite number in the film, a recurring character in her life named Jerome, is played by the equally uncompelling Shia LaBeouf, whose association with the “Transformers” franchise surely helped “Nymphomaniac” get made but doesn’t help it make much sense.

Dreamily drifting from man to man (with von Trier’s camera always at the ready to capture each encounter in fleshy detail), young Joe isn’t on a journey of self-discovery but one of psychic negation, using intercourse as a mechanism to cope with everything from teen insecurity to the death of her father (played in another unconvincing turn by Christian Slater). That intercourse may be explicit, but it’s oddly lacking in carnal passion or pleasure. Neither cynically pornographic or affirmatively erotic, “Nymphomaniac” occupies an oddly lifeless netherworld of un-fun, almost academic, on-screen sex.

With Martin unable to provide much more than her own slender beauty, von Trier injects a fair amount of visual interest in the flashback sequences, adding on-screen graphics and animation to enliven the otherwise often deadly dull proceedings. (He also brings in Uma Thurman for a bizarre, hysterically pitched sequence that only plays up young Joe’s confounding passivity.) But as limited as the scenes of Joe’s past are, her present-day rumination is absolutely riveting, with Gainsbourg and Skarsgard engaging in a fascinating philosophical pas-de-deux — about dominion, desire, morality and selfhood — that shows what great actors can do with beautifully written material.

While Joe tries mightily to seek Seligman’s disapproval for her deeds, and his constant absolution of even her worst sins, the two constantly wander off into lyrical digressions, about fly fishing, trees, music, religion, literature and the unlikely role of cake forks in Hitler’s round-up of the Jews in the 1930s. (Those familiar with von Trier’s outburst regarding Nazism at Cannes a few years ago will perk up their ears when Seligman delves into his own Jewish identity.)

The talk is just that — lots of words bantered about, again supported by von Trier with often beautiful illustrative footage — but Gainsbourg and Skarsgard make it completely their own, creating a compelling, even believable encounter out of von Trier’s most obscure references and arcane ramblings.

“You were reading the river!” Seligman interjects when Joe recalls competing with a friend to seduce the most men on a moving train. Later, when they’re listening to a piece by Bach, Joe uses his disquisition on three-part musical structure to explain her carefully calibrated approach to gratification as a young woman.

It’s an improbably elegant and thoughtful interlude in what otherwise could be read as another of von Trier’s canny attempts to give the audience a few good old-fashioned jolts. The trailer that runs during the final credits suggests that Gainsbourg will have a more central role in “Nymphomaniac: Volume II.” Whether that bodes well for the movie or badly for her remains to be seen.

★ ★ ½

Unrated. At Landmark’s E Street Cinema. Contains explicit sexuality, nudity, adult themes and profanity. No one younger than
18 admitted. 110 minutes.