Gunter Grass had a strange experience while writing his latest novel. "When I do my new book," he says, "from the beginning there was someone speaking behind me and always making his dirty noises.

" 'I want to be in this book! he said. 'I WANT TO BE!" And I said, 'No, no! I don't want you anymore!' It wasn't possible! It just wasn't possible! And this was Oskar Matzerath. Sixty years old, ya? Looking over my shoulder, ya? And he came again and again and again -- and now he's in."

And so the unforgettable protagonist of Grass' famous first novel, "The Tin Drum," a picaresque masterpiece of Nazi horror, is back 27 years later as a minor character in his latest, "Kie Rattin, which translates roughly as "Die Rattin," which translates roughly as "The She-Rat."

Hunching his meaty frame over the remains of breakfast, West Germany's most celebrated litterateur stops to savor this piquant morsel. His dark eyes dance behind granny glasses. The walrus mustache basks on top of a wide, triumphant grin.

"Oskar Matzerath, he's a product of the '50s," he says of the drum-beating dwarf who stunts his own growth in response to the evil around him. "And now we are in the '80s, and the '80s are the result of the '50s. And that's the reason he's coming in. It's his time.

"He is just like he was after the war -- he's a hunchback. But now he's a boss of a media film production company, 'Post-Futurum.' You know, he's always doing well, and this book is just before his 60th birthday."

Grass himself is going on 59, and doing well indeed as a titan of world literature. With his new opus about to be published in West Germany, and an English-language edition planned for this fall, he remains an eruption of plays, poems, polemics, essays, novels -- even drawings, etchings and sculpture. One might say the fiery Grass -- delivering an impassioned political speech here, tossing off an incendiary verse there -- leads a life of volcanic activity.

In the early '80s, "I ordered myself to make a pause -- three years, no writing," he says in blunt, serviceable English that tends to come out in a low rumble. "This was the first possibility I had to go back to my first profession, which was sculpture. This was marvelous to dicover myself after 25 years, going back to the start. But after one or two years, I discovered that I was going on the clay to write. Then this was the beginning of the new book, yes? In the clay.

"I filled up the clay with words. I made pages and pages of clay and I burned them in the fire. Terra cotta, yes? And my publisher said, 'What's that?' And I said, 'It will be my next book -- you have to look for a possibility to bring it out in clay.' And he was sweating. Grass guffaws.

"I like to make jokes like this."

Grass came to New York recently for the 48th International PEN Congress -- a conclave of prominent authors gathered to address the weighty topic "The Writer's Imagination and the Imagination of the State." Even among so many giants of the written work, he managed to loom large in a baggy blue suit, puffing on a variety of pipes and cigars, and projecting a Bohemian air of gemutlichkeit.

"If you come here to America," he says, holding forth in a hotel coffee shop, "you don't feel German the first thing. You feel very European . . . Already, after some days staying here, I discover that in my interior monologue I hear some english noise, yes? It's a special kind of humor, yes? To say something very short and confused -- and the English language is marvelous. I can't give examples. It's too early in the morning for examples . . . "

At a public reading the previous day, Israeli writer Amos Oz had lamented that English translations of his Hebrew works are "like making love through a blanket." Grass, who also was among the readers, suffers no such impediment.

"A good English translation from German makes the German language shorter -- I like this," he says. "The chapter I read yesterday [from "The Flounder"] was in German nine pages, in American eight. And I write a very short German. But English makes it shorter, and this I like very much."

Grass knows just enough of the idiom to get himself into trouble. He says, for instance, that he is "proud" of his fellow German -- "and proud is maybe not a good word for this" -- for continuing to grapple with the meaning of the Holocaust four decades after the fact. "With time distance," says Grass, who as a teen-ager was a member of the Hitler Youth and later a prisoner of war, "Auschwitz becomes bigger and bigger, larger and larger. It grows and grows. It will never be understandable." But then, with the self-righteous fervor of an ex-sinner, he proceeds to preach.

"If it's necessary to do this in Germany, I think it's also necessary in the United States to think about Hiroshima, and not make "Oh yeah, it was a dirty thing, but we had to do it to save lives . . . ' We know all these bloody lies, yes? We have to think about it. Also Vietnam. You can lose a war by military reasons. You can lose it a second time if you don't realize that you have lost the war. And the second defeat is much heavier."

He clearly glories in his role as a left-winged gadfly, and at the PEN Congress he raised eyebrows, as well as blood pressures, with his decidedly unliterary denunciations of western capitalism and the American way of life.

"There is no reason to be afraid of politics, to be in touch with reality, yes?" he says. "And that is one thing about this congress that is like children. You tell children. 'Please play around but don't make dirty.' But I like the dirty boys."

Accordingly, Grass was everywhere to be seen and heard defending the Sandinista regime in Nicaragua, condemning his more conservative colleagues for asking "short-minded, democratic questions" of a Communist Chinese delegate, deriding John Updike's light-hearted paean to the U.S. Postal Service and attacking Saul Bellow's warm endorsement of the American Dream.

"I would like to hear the echo of your words in the South Bronx," he challenged the Nobel laureate from Chicago, "where people don't have shelter, don't have food, and no possibililty to live in the freedom that you have and some have in this country."

"I was astonished at his reaction," Grass says in the coffee shop, still seething over that set-to. "In the morning, I was sitting here with Arthur Miller, and Bellow was passing the table and he said to me that I am silly because I criticized him. And I said, 'Good morning, sir!' . . .

"Now we have the capitalist-state-as-a-postbox, as Mr. Updike likes to do, yes? But to tell ourselves beautiful lies that we still believe afterwards, that democracy gives to everybody shelter, food and freedom -- well, you know quite well it's not true! It is a bad situation when somebody could be able to speak without doubts about the American way of life. But it's happening here, yes? And this makes me crazy."

He seems disoriented by the spectacle of artists -- Updike in his Harvard tweeds, Gay Talese in a dizzying array of custom-tailored suits -- looking as prosperous and respectable as city fathers. "I think that for a writer, it's very good to belong to the loser side. I think in the United States they are belonging to the loser side but they just don't accept it. I didn't believe before that this could happen with writers, but in America the writers take the position of the establishment.

"I think this is a special sickness of the superpowers. Also the Russians are writing in the same manner. If you say something critical about Russia to a Russian -- he's a nice guy and you can drink with him -- but then he's defending things he would never defend by himself, yes?

"The trend is going to neoconservatism in American literature, and I'm afraid this will jump to Europe, too. It's for me a turn to provincialism -- only to see the world as bad 'but our postboxes are working well.' And the literature seems less interesting, generally less passionate. It's always a question of facing reality or not.

"But here is a kind of campus literature, yes? Marvelous-written books about problems of teachers who fall in love with students, and they know how to write it and they make it marvelous, yes? But it's always in this circle, you see, the circle of the campus."

Grass himself has never been one for small, "provincial" books. From his epics -- such as "The Tin Drum and "The Flounder" -- to his miniatures -- such as the 148-page "Headbirths or The Germans Are Dying Out," a dark meditation on Teutonic culture -- they take on all humanity as their subject.

His last big book, "The Flounder," burst forth in 1977 as an earthy, prose-poetic romp through the sexual and culinary history of the species from the primitive epoch to the modern age. Jumping willy-nilly through time and place -- in such chapters as "Why Potato Soup Tastes Heavenly," "Inspection of Feces" and "The Great Leap Forward and the Chinese World Food Solution" -- the novel's protagonist, a talking fish, materializes to proclaim Gunter Grass' great themes.

These, as articulated by the so-called "legendary flatfish," include the meanings of love and war, the moral superiority of women over men, the sociological implications of cuisine, the development of the world's religions -- and much else besides.

"What's funny about a talking flounder?" the author asks. "It's no more funny than a thinking man. If you believe in fairy tales, as I do, there's nothing funny. Fairy tales are much more realistic than all these pseudoanalytic novels we read about three persons in trouble with each other.

"Look at 'Snow White.' In the first version of the Brothers Grimm, it was the bad mother with the mirror, yes? In the second version, it was the stepmother. This is an important change from one version to another, and we have to think about this as a real problem.

"Everybody can understand that a stepmother has to be bad. But we have to go back to the first version -- where it's the mother. It's much harder. I'm interested in questions like this, you see."

In "The She-Rat," Grass deals with no less a subject than the fall of humankind and the rise of a race of rats to inherit the earth.

"The reason I write about them is they belong to human beings," he says. "Rats have long tails. Very intelligent. They don't have to learn their ABC, you see, as we have to do. They know it.

"In my book they are very sad because there are no more human beings, only the rats. Because they always admired the human beings. The human beings didn't admire the rats, but the rats admired the human beings. Then they try afterwards to do what human beings are able to do -- or were able to do before -- to stand up, to go -- yes? -- upright-walking. It's a book about the future."

"The She-Rat" may sound like science fiction, but Grass vigorously rejects any such label. "I don't know," he says, when asked to characterize his work. "It is a book of 500 pages. There is prose and poetry in it. I didn't make a note that it's a novel or something. The critics and the academics -- they may find out what it is."

Since the death of Heinrich Boll last July, Grass has been assiduously trying to escape the mantle of father-figure to his country's younger writers -- a vocation Boll assumed with a sense of duty. Yet Grass holds regular meetings of writers at his town house in West Berlin, where colleagues can read their works-in-progress to one another, and he has endowed an annual literary prize in honor of one of his own mentors, the late Alfred Doblin, author of "Berlin Alexanderplatz."

"I don't know what I can give to younger authors," Grass says. "The same thing that older authors have given to me. You know, I met here for the first time since the '50s, when I was a young unknown author and I visited him in Paris, Czeslaw Milosz. I visited him because I was very touched by a book he had written ["The Captive Mind"] about the dangers of ideologies. For me it was a very important book, not by my literary development but by my political thinking.

"And now I see him here. He is very conservative now. But we had a marvelous conversation. I told him, 'I am your pupil. You teach me in your book. Maybe you don't like this book anymore' " -- he laughs a wistful laugh -- " 'but I still go on like this.' "

Grass and his second wife Ute, a tall, delicate-looking woman who likes to play Buxtehude on the organ, divide their time between West Berlin -- where Grass also has an artist's studio -- and a rambling apartment in Hamburg overlooking the Rhine. At any given time they share these digs with any of half a dozen children from former liaisons, and they are apt to spend many late nights talking in the kitchen -- the spiritual center of Grass' home.

"I like good food," says Grass, an accomplished cook, "but I also make simple dishes at home that my children like. My children are also a little afraid of my kitchen, because sometimes I would really like to cook and eat pig's feet, yes? And braised hearts -- it's good, not heavy. I use everything, not just the filet. and fish eyes -- people should always eat the fish eyes. That brings luck."

There is little enough luck in the world, knows Gunter Grass, who came of age in the midst of war. A native of Danzig, Germany -- a city that today exists only as Gdansk, Poland -- he has long been a citizen of a divided country, a man trying to piece together the fragments of his fractured identity.

"I told you it's very good for the writer to belong to the loser," he says. "You can only write about things you have lost. Like Danzig. That's one of the possibilities of literature -- to write against forgetting. To make time stop."

But Grass' most recent writings have taken on increasing urgency. Confronting the prospect of a nuclear holocaust, he finds himself making books not for the ages, but for now.

"We imagine literature from Homer up from the beginning of the century, we always had one marvelous ally -- time," he says. "The future was on our side always. Censorship, it didn't matter. In 100 years, in 150 years. Diderot, Voltaire -- they could wait, yes? Their books will say.

"But this has changed. We don't have this anymore. I know very well we can't go back and make agitprop literature, yes? But you also cannot believe that literature will have this time, this '100-years-from-now,' this eternity that our nice beloved Baroque authors always had. This is the first time in our life as human beings that we are able to destroy ourselves. And we are able every day to do it -- every day."This has nothing to do with apocalyptic things, with being afraid of the dark, things we are not able to handle. You see, it's all very, very clear. In the daylight. We know it. We have done it. And only we can turn it away."