I see you need a firm hand.

Belle de Jour is a film of interiors, from the cold, stylish apartment occupied by young bourgeoise couple Severine (Catherine Deneuve) and Pierre (Jean Sorel) to the deceptively mundane hallways and parlor rooms of the brothel where Severine works every afternoon to the lurid sadomastic fantasies that comprise her interior life and which increasingly blur with the film's reality. While sex is omnipresent in cinema, it is too often merely titillating, its possibilites as a form of communication and artistic expression rarely explored. In Belle de Jour, Luis Bunuel uses signifiers of sexual desire to communicate his protagonist's interiority, Severine's fantasies and attempts to enact them revealing her as a character lost in her own mind. A landmark work of erotica, the film revels in its constructed sexuality even as it uses its more provocative moments not to bring us closer to understanding Severine but to make the source of her mysterious, implacable desire more and more elusive. Its eroticism lies not in what it shows but in everything it leaves hidden.

Chief among the film's exquisite surfaces is the perfect, porcelain face of Catherine Deneuve, whose refined sexual persona was subverted throughout the 1960s by directors like Bunuel, Jacques Demy and Roman Polanski. In Belle de Jour, Severine's cool elegance masks a highly active fantasy life comprised of banal pornographic scenarios involving her rape, torture and degradation. Severine's air of propriety - she complains about flirtatious family friend Henri (Michael Piccoli) that "I don't like the way he looks at me" - is punctured when, after an offhanded mention from Henri of the city's secretive upscale brothels, she finds herself in the home of Madame Anais (Genevieve Page) asking for a job. Bunuel contrasts the bored, idle chatter of the other women at the brothel, whose motivation seems more economic than sexual, with Severine's more urgent need. Afraid at first, Severine is soon drifting from client to client with a dreamlike detachment, any inner conflict demonstrating itself not in big emotional scenes but with smaller moments, as when she peers at another prostitute at work, claims disgust and then turns back to continue watching. We're given flashes of Severine's childhood - an incident of sexual abuse, a Catholic moment - but they're not meant to explain her, and Bunuel avoids any overt psychoanalysis. At the heart of all of Bunuel's films is an inexplicable mystery; here, it's the source of desire.

Also key to Belle de Jour is the way that individual desire becomes codified, particuarly for women, whose sexual fantasies are inevitably projected through a distinctly masculine lens. Severine's fantasies are straight out of the yellowing paperbacks of the period, the main difference being that we are made to identify with the tortured rather than the torturer. Her own attempts at realizing her fantasies are filtered through the very particular fetishes of her johns, enacting fantasies of sadism, humiliation and even necrophilia. It seems as though Bunuel is saying that female desire - and, by extension, female identity - is inextricable from the male gaze. This blurs into Severine's everyday life - the husband who remains oblivious to her afternoon job (hence her work name) so long as she's waiting when he returns from work, the older man turned on by teasing her propriety who loses interest when he learns of her carnality, the gangster (Pierre Clementi) who aims to own Severine both at work and at home. Bunuel retains his bemused perspective, leaving us to sort out the film's complicated sexual politics. When Severine seems to finally find what she's been looking for, in the famous scene involving a Japanese businessman and his mysterious black box (written about in greater detail by Belle de Jour's number-one fan Paul Clark), the film reveals the most even as it becomes ever more elusive. Foreshadowed in young Severine's rejection of communion, Severine's ecstatic gaze, the sense that she has crossed an invisible line, is a sensual refutation of the Eden myth; it is only through the unknown, the thing which cannot be codified or explained away, that Severine can finally come.

Though Belle de Jour is a very sexy film, there's very little skin on display. Its success lies in the way that it tantalizes our imaginations in the same way that Severine is compelled by the promise of unknown experience. As is often the case with Bunuel's work, its ambiguities and deliberate confusion of reality and fantasy exposes our own absurd adherence to convention even as we desire to break free. Its final scene, with its masterful collision of images and sound, suggests that Severine has only scratched the surface of a need that will never truly be fulfilled. It's a perfect representation of how desire is bound to identity and leads us to reflect upon our own fantasies and how the stranger they are, the more they define us.