She is wearing an olive-colored suit. Her hair is a blond thicket bound around her head with yellow butterfly clips. Her blue eyes are direct, and faraway, too. And she has freckles. Close to her, she holds her month-old daughter, Gracie, swaddled in a shawl, and she says, “She’s really a sweetie. She’s much more sensitive than my other kids, more sensitive to touch and noise. This one is so skittish. She’s like a pixie.” Not skittishly, Gracie sleeps in the cool and quiet of this room. That image, and the seeming ordinariness of it, touches you in the same way her new film, “Heartburn,” touches you, or “Sophie’s Choice,” or “Kramer vs. Kramer,” or “Plenty.” You feel that Meryl Streep, simply with her presence, is telling you the truth, not just about her life, but about your own.

“DIRECTING MERYL STREEP,” says Mike Nichols, who has done so twice, once in “Silkwood” and now in “Heartburn,” “is so much like falling in love that it has the characteristics of a time which you remember as magical and creative and of which you’re extraordinarily grateful, but which is shrouded in mystery. I don’t remember the things that she said and that I said.” What does this private glimpse of Meryl Streep have to do with acting? Everything. “What we see on the screen,” says Nichols, “is the actor’s nature, the actor’s essence.” “I used to have a little thing that I said to myself early on, when I was in ‘Deer Hunter,’ ” Streep says. “I was just casting around for anything to get me through, and this little thing came to me. I say to myself, ‘Be who you are and know what you know, and that’s all you have to do. That’s the entire job.’ Suddenly, I became potent. Oh, it sounds completely simple-minded. I told it to somebody else, another actor who was in terrible trouble, and he said, ‘What the hell does that mean?’ But that’s all I’m doing, really.”

BECAUSE AN ACTOR’S most precious asset is his very nature, he has to fight to protect it. Different actors work differently. “You get to a certain point in your life,” Streep says, “and a certain amount of accomplishment and fame and notoriety on the streets of New York City, and certain people are gunning for you for that reason, other people are more willing to like you than they should be. I have to insulate myself from all that stuff, I have to get away from it. I have to really hide out and keep myself safe from whatever the evil forces are. “I really admire these people who are right out there, like Jack (Nicholson) or Mike (Nichols). They keep their pores open to experience. They’re both sort of hungry all the time for experience and people. They devour people, events, the hurlyburly of New York, all that stuff. Los Angeles. I’m really impressed by that! I can’t do it.” What Meryl Streep is doing is creating a new person every time out, from Sophie of “Sophie’s Choice,” a Polish emigre wounded by history, to Susan of “Plenty,” a former British spy wounded by her own exaggerated hopes for life; from the randy nuclear activist Karen Silkwood to the repressed writer and adventuress Karen Blixen. She’s doing the kind of character work that you associate with an Alec Guinness, while retaining that elusive, romantic quality you associate with a movie star, that ability to move and enchant us. “It probably has to do with my world view,” says Streep, “which is that everybody’s different, but they’re all the same in some way. I just like to investigate all these different people to see what the commonality is with me. When I start with the script and I read their story, I hear the ‘Ping!’ that makes a connection with my own life or experience. It’s heartening to be embarked on this look at all these different women. That’s my secret pleasure in it.”

THE IRONY OF MERYL STREEP’S career is that it is precisely her skill that has led to a backlash against her. Her critics have charged that she always seems to be watching herself in the mirror, that her performances are too “worked out,” that you can see the machinery working. It’s as if we’re so used to dividing performers into movie stars, who grab us with an expression of personality, and character actors, who play a role, that we persist in believing that someone like Meryl Streep simply can’t exist. You’re struck first by her exquisite ear. Not only the accents, but the intonations and rhythms, and even the timbre of her voice, change from role to role, so that she captures not just a way of speaking, but a way of thinking that the speech reflects. “In ‘Sophie’s Choice,’ ” says Nichols, who was born in Germany and whose first language is German, “Meryl spoke perfect German, with only a trace of a Polish accent, very fast. Now that’s not supposed to be possible.” In “Plenty,” her voice evoked a species of shrill craziness that is peculiarly British. In “Out of Africa,” her voice, besides carrying an impeccable Danish accent, became an expression of the process of aging. And for “Heartburn’s” Rachel, it means talk that is, in some undefinable sense, identifiably Jewish.

STREEP’S STYLE, THOUGH, goes beyond her voice, to the expression on her face, and when it’s expressive and when it isn’t; to the way she carries herself, and the way she moves. In “Silkwood,” she’s all jut and angles; in “Kramer,” stiff and tentative; in “Plenty,” sinuous and loose-limbed, and graceful as a bird. “When we were working on ‘Heartburn,’ ” says Nichols, “I would see her fall onto her knees with the drawer with the evidence of her husband’s infidelity — weeping, whining, completely naked emotionally — and I would think, ‘That’s the real Meryl, that’s Meryl exposing her heart.’ And in the middle of working on the rough cut, I saw ‘Out of Africa.’ When she received the news of Finch- Hatton’s death with this barely perceptible tremor in her cigarette hand, and went back to reading, I thought, ‘No, that’s the real Meryl.’ The truth is that it’s all the real Meryl, and she can actually change herself within.” As in, for example, this deceptively simple scene from “Heartburn,” in which Rachel, pregnant with her second child, feeds her daughter and asks her father’s maid if she’ll take care of her for the day. ‘ There’s something in that scene that goes beyond technique. Like much of “Heartburn,” a movie where character is plot, and everything happens between the lines, the surface has nothing to do with what’s really going on. The chatter hides the crisis of a woman whose world has just fallen to pieces, and who is trying to figure out how to put it back together. “It’s very complicated, that whole thing,” says Streep. “It’s about this mess that your life turns into when you let down your guard and let yourself be loved, or imagine that you are, and then whammo. But as high as your rage is, you still don’t want to leave. That’s a terrible position to be put in.” Amidst all the technique, what remains elusive about Meryl Streep’s acting is a resonance that even directors who have worked with her find mysterious. “If there is a character and there is a critical moment, and in that moment there are seven different emotions, a very good actor will show you all seven emotions,” says “Kramer” director Robert Benton. “A great actor will show you one or two of those emotions, and the blank spaces you will fill in, like a Matisse drawing. The greatest actor will show you that in fact it was not at all the emotion that you expected, but something else that so illuminates the moment that you find out something not only about the character, but about yourself, and life. And that’s what Meryl does.”

“THE WHOLE NOTION of being pregnant and with a little child and being in that kind of trouble in your marriage is so charged,” Streep says of her role in “Heartburn.” “I felt that vulnerability that you can have in a pregnancy. It’s pretty amazing. You really let down your guard and you sort of have this tacit agreement with your husband not to let certain things count, like how pretty you are. You know, for a certain amount of time, he’s just gotta bear with me here, this is the way it looks. And with that letting down your guard you really let the doors open. For somebody to be unfaithful is tough, but in that time . . . . I would have been just jelly. So I had a feeling for what that would be like. It upset me every time I thought about it, so it wasn’t that hard to imagine.” Gracie snoozes in her shawl, and with the child in her arms, she is a mother, and with her giggles, sweet sixteen; with her wise eyes, an old woman, a?M J^rli „ emotional nakedness, a kind of rare child able, says Nichols, “to walk through any crowd, any situation, right up to you, look you right in the eye, and be right there with you, and deal with anyone or anything.” She is simply Meryl Streep, and God only knows what that means.