British actress Keira Knightley joked on Friday that she drew on her own madness to play a deranged heroine in David Cronenberg's "A Dangerous Method" which premieres at the Venice film festival. Knightley's harrowing performance as Sabina Spielrein, a young woman who suffers from hysteria before she is treated by -- and has relationships with -- both the psychologist Sigmund Freud and his pupil Carl Jung, stole the film. "Did I enjoy playing a deranged character? It was great fun. I'm obviously crazy anyway, so I drew on that," she quipped following an advance screening of the film, in competition for the Golden Lion award at the world's oldest film festival. It is Jung, played by Michael Fassbender, who first comes across the passionate and violent Sabina, an 18-year-old Russian who speaks fluent German. Intrigued by her intelligence and beauty, he begins trying out Freud's talking cure on her, but is soon dangerously captivated by the beguiling woman. Jung's budding friendship with his mentor Freud, played by Viggo Mortensen, is eventually compromised not only by increasing differences in opinion on the future of psychoanalysis, but also by his affair with his patient. Based on historical events and adapted from Academy Award winner writer Christopher Hampton's stage play "The Talking Cure", Cronenberg's film plays heavily on the carnal drives which overpower rationality and learning. Scenes where letters are written back and forth between two of the 20th century's great minds -- the letters on which the screenplay was then based -- are followed by scenes of erotic violence, where ink is replaced by blood. Cronenberg, whose works include the dark thrillers "Spider" and "A History of Violence", acknowledged his latest film is different from the others, saying that it may well appeal more to Freud and Jung followers than to his fans. But he said: "My basic principle has always been the same: I give the movie what it wants. I just shoot the movie that asks to be shot." With "A Dangerous Method", Cronenberg said he had sought to make "an elegant film that trades on emotional horror but loses none of its power to seduce".