Watching Keira Knightley all prettied up in "Pride & Prejudice," a new adaptation of the talky 1813 Jane Austen novel (see review on Page 45), may come as a bit of a shock to those who are just coming off seeing her in "Domino," in which she plays the gun-toting, biker-chic Hollywood scion/model/bounty hunter Domino Harvey, or to those who remember her in tattooed fighting form as the arrow-slinging Guinevere in "King Arthur." To the 20-year-old British actress, whose performance in "Pride" has been compared to that of a young Audrey Hepburn, there are more similarities between the roles than meet the eye.

"There's this great wit in the book," says Knightley, speaking by phone from New York, while on break from shooting the upcoming "Pirates of the Caribbean: Dead Man's Chest," a sequel about whose secrets she's scrupulously tight-lipped. ("I'm not telling you anything," she says. "You'll just have to see the movie.")

"That wit," she continues, "provides Austen's characters with this amazing strength. If you can use your mind like a weapon, you don't need to run around with a machine gun or a sword."

Not that she has a problem with either. Knightley, who most admires such old-school actresses as Bette Davis and Katharine Hepburn, is particularly -- one might even say perversely -- proud of the fast-paced, explosive "Domino," even though it was not received kindly by very many critics. "If you believe the good reviews, you have to believe the bad reviews, too, but neither is particularly helpful," she says. Calling herself her own worst critic, Knightley says she's "fiercely proud and protective" of the Tony Scott film, which she believes will someday find its audience. "That film belongs in an art gallery," she says. "We knew from the beginning that people were not going to like it."

About "Pride," on the other hand, she's more sanguine. "I'm fairly confident that you will at least like this film, and you're probably going to love it." Still, she's a realist. "You're never going to make a film that everyone likes," she says. "That's what's so beautiful about film."

Come again?

Knightley explains that it is the very process of creation -- and, at times, failure -- that exhilarates. "It's all terrifying," she says. "You don't want to [expletive] it up, and you are going to [expletive] it up." The tension between the possibility of victory and the certainty of (at least partial) defeat, coupled with the idealistic belief that art, at its best, can "change the world," comes largely from the 1960s- and 1970s-style idealism she inherited from her parents, actor Will Knightley and actress-turned-playwright Sharman Macdonald ("When I Was a Girl, I Used to Scream and Shout").

So, "Pride & Prejudice" is going to change the world?

"Jesus, no," she laughs. "It's a lovely bit of escapism though." Rather, Knightley points to such movies as "Capote" as examples of art's power. "It's completely sensational and disturbing," she says of the new film starring Philip Seymour Hoffman as the famous writer, "because it shows you that people aren't good or bad, but both. In a lot of movies, there are the goodies, and there are the baddies. But the reality is that we are all various shades of gray."

She even views "Pride's" Elizabeth Bennet with a bit of ambivalence. On the one hand, Knightley says, her character's refusal to marry the odious but financially advantageous suitor Mr. Collins (Tom Hollander) can be seen as selfish, but that decision also "defines" Elizabeth, she believes. Her character's strength, Knightley says, comes from the fact that "she cannot be anyone other than who she is."

Calling herself a feminist, but "in a quiet way," Knightley finds what she calls today's anti-feminist backlash -- the retrograde notion that "women can't be happy without a man" -- completely offensive. "I can be perfectly happy without a man, thank you. In the days of Jane Austen, though, who many say was the first feminist, the only job a woman could get was marriage. What [Elizabeth] does is to say, 'I'm not marrying without love.' That's a huge thing."

"Love Actually" notwithstanding, Knightley's not much of a fan of today's romantic comedies. Again, it's because too many times the blade of the script is dulled by crassness. "We don't do wit," she complains about most of today's commercial multiplex fare. Still, it's the constant variety of choices she has made, from light comedies to visually arresting action films to brainy romances, that keeps her interested -- and her life interesting -- even if it means lots of hard work, even for someone who has been at this particular profession since childhood.

Knightley recalls, with fondness, a particularly elaborate and lengthy shot from one of "Pride's" ballroom scenes in which director Joe Wright's camera swirls in one continuous movement, for minutes without a single edit, among the guests. That scene, which required nine arduous hours of rehearsal and 13 takes, was "incredible," she says, "extraordinary."

Equally fun, but for a different reason, was the chance to lose all the hard-fought muscle mass she put on for "King Arthur's" Guinevere, a role whose buff physique and demanding stunts, which Knightley performed herself, required a regimen of daily workouts and a high-protein diet.

"It took me a good year and a half to get back after that," she says, adding that the return to her "normal eating habits" and sylph-like figure was made especially palatable by a couple of things that have nothing to do with acting or discipline. "Pasta is key," she jokes. "Pasta and red wine. I'm not allowed to drink that over here, but in Europe I'm allowed. It's the best diet around."

"Wit provides Austen's characters with this amazing strength," Keira Knightley says of Jane Austen's novel "Pride & Prejudice."