On the one hand, it does seem a little out of character for David Cronenberg, the Canadian director best known for his intense, disturbing genre work, to offer up "A Dangerous Method," a chatty, disciplined period piece about the birth of psychoanalysis. On the other hand, what took him so long? Cronenberg's oeuvre has certainly been evolving in this direction, with pauses to consider such topics as mental illness (2002's "Spider"), emerging science (1986's "The Fly"), and compulsive kink (1996's "Crash"). Plus Cronenberg has been on a critical and commercial roll in recent years, his last two films ("A History of Violence" and "Eastern Promises") both earning Oscar nominations as the one-time horror auteur moved into mainstream filmmaking. Well, mainstream-ish, anyway.

To that end, "A Dangerous Method," which explores the tenuous professional friendship between Sigmund Freud and Carl Jung, is fitting Cronenberg territory, rooted in themes of emotional violence, dualism, and sex. The film opens with a flourish in the summer of 1904, as a wildly unhinged young woman howls and writhes her way in a horse-drawn coach to Zurich's Burghölzli Clinic. She is Sabina Spielrein (Keira Knightley), a Russian émigré upon whom Dr. Jung (Michael Fassbender) plans to try Dr. Freud's unorthodox new treatment known as "the talking cure," which gets to the root of a patient's issue through analysis rather than zapping the madness from them. Even through her tics and spasms, it's obvious that Spielrein is both lucid and brilliant, and before long she's assisting Jung with his research.

Flash forward two years; Spielrein is a medical student, and Jung finally gets to meet his Austrian mentor. As deftly channeled by Viggo Mortensen, the calm, cigar-chomping Freud embarks on an extended exchange of ideas with Jung, whom he initially refers to as his "son and heir." Yet despite their common ambitions, the colleagues diverge on many theories; the open-minded Jung is annoyed by Freud's immoveable stance on sex as the basis of all neuroses, while Freud is unhappy with Jung's interest in speculative sciences like telepathy and parapsychology. And there's a class difference simmering between them as well, with the middle-class Freud keenly attuned to his position of power over the wealthy Jung and unwilling to jeopardize it.

Spielrein, meanwhile, has become the married Jung's lover, and "A Dangerous Method" observes as the resentment between the two men boils over once the now-scorned Sabina announces her intention to move to Vienna and study with Freud. The astute, provocative script by Christopher Hampton ("Atonement"), based on his stage play "The Talking Cure" (which was, in turn, inspired by John Kerr's 1993 non-fiction book "A Most Dangerous Method"), allows the story to unfold through a series of thoughtful conversations between the parties in various pairings. The most interesting dialogue, unsurprisingly, occurs between Jung and Freud; it's always a little thrilling to see historical watershed moments recreated on screen, especially by two actors at the tops of their games.

But matters of sex and dreams and anal fixation usually take a back seat to the more cinematically pedestrian Jung-Spielrein affair, which is only slightly less successful than the famously rocky bromance since Mortensen and Fassbender enjoy better chemistry than do Fassbender and Knightley. (Although the wily Vincent Cassel shows up and threatens to put them all to shame as Jung's hedonistic patient/associate Otto Gross.) Fassbender plays Jung as the proper Protestant wrestling with honor, fidelity, and the uncharted world of analytical psychology, while Mortensen delivers perhaps his finest performance as the wise, vain Freud. Knightley may immediately alienate some viewers with her bug-eyed portrayal of a woman in heavy emotional distress, but she gets better as Spielrein does, eventually emerging as the heart of the film and the corporeal representation of the two titans' most enduring concepts.

Technical work here is all-around excellent, from the exquisite Edwardian-era costumes and set design, to the atmospheric lighting, to the evocative photography by Cronenberg's longtime cinematographer Peter Suschitzky. And if I haven't mentioned much about Cronenberg himself, it's because "A Dangerous Method," with its visual restraint and drawing-room milieu, doesn't feel like what we've come to call a Cronenberg film; it's more akin to Merchant Ivory, but with just a pinch of bondage.