"I was three or perhaps four years old when I realized that I had been born into the wrong body, and should really be a girl."

That is the startling opener of Jan (formerly James) Morris' account of her longing, from earliest childhood, for sexual transformation. Most of us, strangers to that obsession, find it a weird and uncomfortable subject. And not only such deep disorders of sexual identity as afflicted the eminent British journalist, but the question of sexual roles and identities generally.

I have encountered people who are resolutely avoiding Dustin Hoffman's hilarious new movie, "Tootsie," which treats the subject satirically. It may be good, they say, but the subject is vaguely ominous.

In fact, the mild role-reversals in "Tootsie" have little or nothing to do with obsessions to cross the Adam-Eve barrier permanently. It is the urge to survive chronic unemployment, not transsexual longing, that leads the unemployed actor Michael Dorsey (played by Hoffman) to create "Dorothy Michael," who then becomes a hot soap-opera star.

Since it deals playfully with a powerful social taboo, this movie could have slipped into the usual coy farce or slapstick. Yet it is completely controlled and disciplined--a thoroughgoing dramatic success.

"Tootsie" is, in fact, a Chinese box tour de force: Hoffman is an actor playing an actor impersonating an actress playing a soap-opera role. It is a risky role, but Hoffman performs it brilliantly. Moreover, once Hoffman's hero puts himself, rather shakily, into corset and high heels, there is a sort of Pygmalion Effect. It is this that makes the film, if you will pardon the heavy-handedness, interesting.

Hoffman's Michael Dorsey doesn't exactly fall in love with his female double: his creation Dorothy is no Galatea. But he gets to like his creation well enough to be stung when people make slighting remarks about her looks or personality, call her plump or a "wimp." When he has finally bailed out--the pretense has become unmanageable--he says: "I was a better man as a woman." Hoffman has been saying much the same in recent interviews.

Whatever preachy point about feminine assertiveness Hollywood thinks it has worked into the story, the real point seems to me less hackneyed. The good news about "Tootsie" is that it takes on the uncomfortable tyranny of rigid man-woman roles, and actually leaves you with a pleasant and paradoxical point about them.

Stereotyped sexual roles are perhaps less rigidly insisted upon in American society than they were 25 or 30 years ago, but they still exercise a tyranny, even when satirized. (One thinks of the dress-up revues that are said to afford after-hours levity at all-male enclaves.)

Without plunging into the murky depths of psychotherapy, one way of putting it is to say that Hoffman's actor, playing "Dorothy Michael," has given a workout to his "anima." That's Jung's metaphor for the bottled-up female spirit that lurks in every male, no one being absolutely one or the other. It is also the idealized woman inside every man.

Most of us, fortunately, are completely at home with our sexual identities. Oh, we might enjoy some mild flouting of male-female stereotypes--ironing or vacuuming, let's say --but are faintly embarrassed if our friends catch us at it. Most men have difficulty discovering their Dorothy sides, hence never discover the interesting paradox that they're better men for doing so, which is the old point that "Tootsie" makes in a fresh way.

"Tootsie," in short, isn't so much about sexual confusion as it is about sexual clarification, the kind of clarification that comes from imaginative role reversal. This was once, presumably, a commonplace of the stage: in Shakespeare's time and later, men often played women's roles.

"Tootsie," perishable as it no doubt is, uses that old comic convention to make a thoughtful point about the benefits of imagining yourself on the other side of a barrier.

Adam, may I present Eve?