Although his prodigious energy is now channeled into healthy outlets such as working out, a few traces of the erratic adolescent of his past remain. And, subtly, Downey acts as if he's still running on borrowed time. It's the way his eyes alternate between staring intently and darting around the room, or how he nervously mauls a straw in between cigarettes, or the fact that he skips the mushroom soup for fear of candida. Nonetheless, he is better. Much better. And looking swell: His agile body is compact and well-sculpted; his hush-puppy brown eyes are ever so flirtatious; and he exudes and aura of positive energy that is not chemically induced. "I am so happy to be alive right now," he gushes euphorically. "This is the most sought-after of all periods, the Golden Age, a time of real heroes, the year 2000. I'm so into it. Sometimes I wake up in the morning and start barking!"

The new-age terms and allusions to psychology that occasionally punctuate his conversation might lead one to assume that Downey has undergone either a 12-step program or intense psychotherapy. But it turns out that the actor's true savior is a mustachioed man who passed away some years ago, a foreigner with a funny accent. No, not Freud.

"Charlie Chaplin was, is, really about healing through entertainment," Downey says of his mentor, whom he portrays in Richard Attenborough's epic biography, Chaplin, due out this Christmas. "Chaplin was desperate but charming. He had a great sense of self-esteem, knew right from wrong, yet was still a bit of a goat at times, not above picking up a cigarette from the floor if he wanted it. I don't think there has ever been another time when the whole planet could relate to one thing."

Discussing Chaplin, Downey is religiously focused, obsessed even. "I keep going back to the basics, like archetypes," he continues. "I think that Chaplin and Adolf Hitler pretty much wrap up the 20th century. And just in case we wouldn't get the metaphor, God made sure they looked alike."

The role, Downey says, infused him with a sense of purpose: "I will never do another Chances Are or Air America again. I'd sell my house before I made a movie that didn't feel right... Part of me feels that acting is my job - a damn good living, and I don't want to give up the lifestyle - but another part is just starting to recognize the tertiary, healing, element to art. I have to believe that there's something, some greater purpose, for my doing it, because, really, nobody has any business playing Charlie Chaplin."

Apart from Buster Keaton, no one has ever come close to approximating the physical comedy of Chaplin. For Chaplin, which spans more than 50 years of the comedian's life, Downey, a natural mimie himself, had to relearn everything from walking to talking to sitting down. "It was like living the Tiffany book of table manners," he recalls. Some of the most challenging moments? Wearing prosthetic makeup on his face, and hands for two weeks; learning to play the cello and tennis left-handed; and, of course, the accent. "You can't improvise in Cockney unless you're Cockney," Downey points out.

The advance word is good. In fact, Downey captures the Little Tramp so well that Attenborough opted to intersperse the movie with original Chaplin footage. And when Geraldine Chaplin, Chaplin's real-life daughter, who plays his mother in the film, saw Downey's screen test, she was dumbstruck: "Robert has the same silhouette, the same way of standing, the same way of pondering. And the way he moves, his hands, everything," she later said.

Their physical similarities notwithstanding, Downey also draws odd parallels between their lives, starting with a mutural love of music. He mentions, for instance, that at the end of his life, Chaplin rescored all his movies. And while Downey, whose favorite class in high school was Madrigals, is not yet a serious composer, he claims to want to be a musician. "Not a rock star," he insists. "There's a song-and-dance man in me." To that end, he has recorded a lively pop interpretation of Chaplin's sentimental song "Smile," which will be released on the movie's sound-track album.

Downey identifies with Chaplin in other ways. "Chaplin came from Victorian England, when it was perfectly acceptable to have young wives, young mistresses, and prostitutes - especially in the theater. When he married Oona O'Neill, he was being judged in the context of the moral standards of a foreign country, so he was really a 'stranger in a strange land'." Downey, too, considers himself an outsider. Mention "brat pack," for instance, and he growls: "I am completely and happily not in the loop of my peer group. I don't go to their houses for Super Bowl games. I don't know where they go; they don't know where I go. Think of me as the Switzerland of the under-35-actor's community."

The son of an underground "antiestablishment" filmmaker, Robert Downey Sr., and an actress mother, Downey, along with an older sister and a cat named Kubrick, grew up in an unconventional, chaotic household. The family moved frequently, taking up residence in such bohemian enclaves as Greenwich Village and Woodstock, NY. As a child, Downey Jr. began appearing in his father's cynical and absurdist films, his first role being a canine in Pound. Some of these films achieved a respectable measure of success - allowing the Downeys to live the high life occasionally - but the majority were commercial failures. "My father always said that money isn't important," he sighs proudly, a soupcon of self-doubt apparent. "I'm in a very precarious position now of having made a lot of money not knowing its value. It's going to be very uncomfortable for me to stick to what I believe," he says.

Sometime during the late 70's, his parents split up ("It's all a bit foggy," he says), and Downey landed in Los Angeles, only to drop out of high school a few years later to pursue an acting career back in New York. In interviews, Downey has said that his father enjoys working with him because he is willing to try anything. But this same open-mindedness got him in trouble in his personal life. "Let's just say that drugs are a symbol for a spiritual deficiency," he comments.

Actress Sarah Jessica Parker, Downey's seven-year, live-in girlfriend suffered through much of this "Dionysian" period, which included several visits to rehabilitation programs. "I was a nightmare," he concedes. She stayed with him until last year, reportedly until he got on his feet.

Then, last Memorial Day, just months after Parker had left him, Downey married another actress whom he had known a long time, Deborah Falconer. "I'm sure that in some ways my marrying as quickly as I did might have seemed an affront to Parker," Downey offers. "But both of us knew that we were not meant to be." They are still good friends, he assures.

Downey's spiritual maturity coincided with the fine-tuning of his acting. In Chaplin, surrounded by such giants as Anthony Hopkins and Kevin Kline, Downey was "challenged artistically. This was the first time I admitted that I didn't know what I was doing," he remarks, turning on the new-age actorspeak: "You know, change only occurs when you move out of your comfort zones." It's Attenborough ("He's Yoda, and I'm Luke") who gets all the credits: "Fifty years of experience comes through him. He single-handedly taught me that pure intuition can sometimes be cavalier, that a lack of repetition and preparation does not necessarily make for a spontanious performance."

Often the process was overdue, to the point of being humiliating. "There were times when I just thought, 'Oh my God - I'll never be able to show my face again. I don't know what I'm doing, and everyone's gonna find out - that imposter-complex thing," Downey notes. "But every day I just sat with the fear, because, underneath it all, more than anything, was a great desire to be a catalyst in the reigniting of Chaplin's spirit. Because he's coming back, he's coming back for Christmas."

It's been months since Chaplin wrapped, and Downey Jr., self-esteem improved, had made an exceptionally witty and irreverent documentary aobut the 1992 presidental elections called The Last Party; worked with director Robert Altman on his new film, Short Cuts; and, of course, gotten married. Still, he finds himself obsessing, watching Chaplin movies at night, and constantly finding new links to his mentor. "A lot of people think that I have to let this Charlie thing go, so I can move on with my life," he suggests. And when he finally does, he'll probably reach that secure place where he longs to be. But in the meantime, "There's still so much to learn. As they say, it ain't over till it's over."