To some extent, this was an unfair expectation, for how many corrosive comic actors have ever triumphed for long over the homogenizing effects of Hollywood? Most of Murphy's "SNL" colleagues (Chevy Chase being only the most conspicuous example) lost their edge in the movies and became entrapped in the muck of family entertainment.

But there were also rare exceptions, such as Aykroyd, especially in "Driving Miss Daisy," and Bill Murray who developed into far more accomplished, far more mysteriously gifted movie performers. When you see Murray get inside his spooky silences and open himself up in "Lost in Translation," you realize you're watching a transformation that is at the very heart of acting.

It took a while for Murphy to achieve this kind of audacity and come into his own as an actor. Because he came out of stand-up and sketch comedy, he learned early on to coast on attitude; there was little continuity of character in his performances. In "Trading Places," for example, we never see in the successful businessman the foul-mouthed vagrant he once was. It's like watching two different actors.

But then there is "Bowfinger" where he plays, among other roles, a relentlessly paranoid movie star who is clearly a ruthless send-up of himself and his very public problems, or "Life," where he plays with total authenticity a convict who ages 40 years in the course of the movie, or "The Nutty Professor," where the pairing of decorous, fat-suited Sherman Klump and his testosterone-fueled alter ego, Buddy Love, defines the yin and yang of Murphy's career (and also of African American personas in show business).

It's one of the most startling comic performances on film, right up there with Steve Martin in "All of Me." With his brown jacket and bow tie, his chuckling low voice and Oliver Hardy-like gracefulness of movement, Klump is determinedly old school.

Murphy has a deep-down affection for this man. His Buddy Love, on the other hand, with his body-tight duds, hyperventilated hyena laugh and propulsive patter, is Murphy's nightmare unveiling of his inner imp. As is often the case with Murphy at his best — or even much lower down, as in "Norbit" — what at first seems like blatant racial caricature turns out to be much more complex and emotionally nuanced.

As James "Thunder" Early in "Dreamgirls," Murphy hasn't split himself in two — or three or five. He is playing a man who is triumphantly, tragically himself.

He is also playing, for the first time in his career, an artist and perhaps this explains the ferocity and despair with which he attacks the role. Early is an ecstatic entertainer self-immolating in his own spotlight; the sheer sexual pleasure of performing has rarely been so well expressed.

This is why, to protest his new, sanitized self, Early drops his pants onstage in exultant protest. This is why, when he gets the word that his soul sound won't cut it anymore, he shuts down right before our eyes. He pulls out the heroin and prepares for dreamland, and the ravaged look in his eyes tells us he's not coming back. This is not Early's final scene in the movie but it should be. It's his poisoned valedictory.

Murphy is totally exposed in this film — there are no fat suits to act as a poultice.

Sometimes actors reach so far inside themselves that they are left bewildered by what they have brought forth.

This performance as James "Thunder" Early is the latest, and most confounding, chapter in our long and complicated relationship with Eddie Murphy. He is only 45. May the complications increase.