JAMES BALDWIN--the foremost black writer of his generation--is having trouble with words this particular evening. They aren't coming easily and they're separated by long introspective pauses or plaintive sighs. Time and again, he starts a sentence, qualifies it, abandons it mid-thought, starts another, abandons that one, too, before reverting to the first, which he carries with palpable effort more or less to its conclusion.

Then, his voice like a whisper of wood smoke at dusk, he asks, "Am I making myself clear?"

The 59-year-old author, whose essays and novels brought home to much of America in the 1960s the urgency of its race problem and the smoldering passions of the dispossessed, has come to Washington to oversee the final preparations for "The Amen Corner." A new musical based on his play of the same name (the first he ever wrote), it previews tonight at 7:30, tomorrow at 2 and 7:30 p.m. and Sunday at 3 p.m., then opens a six-week pre-Broadway run Monday night at Ford's Theatre. But it does not seem foremost on Baldwin's mind, as he settles into a plush banquette in the dining room of the Embassy Row Hotel.

Two weeks ago, he was in St. Paul de Vence, France, where he spends at least half of every year in a stone farmhouse that is home when he's not staying with his brother in Manhattan. Jet lag still dogs him. He stares at the oversized pink menu, drifting away in his private reveries. In the quiet dining room, where the waiters come on little cat feet and the only sign of life emanates from a party of Germans a booth away, his silence is deafening.

"I'm used to menus in French, so I'm translating," he says finally. "I think I will simply surrender and have lamb chops and a green salad." He leans back, as if relieved to have the decision behind him.

"Since arriving here, I have been in an airplane, on the road, in a hotel, in a couple of beds. C'est bizarre. Je suis toujours en train de penser en franc,ais. Il faut que je fasse un acte de volonte' pour parler l'anglais." Which translates as, "It's strange. I'm still thinking in French. I have to force myself to speak English." But, apparently, the French language offers neither solace nor assistance this evening. A few minutes later, Baldwin drops it with a casual flourish of his graceful hands, the way a stripper drops a chiffon veil.

And he sighs again.

A great part of him, he admits, is still absorbed, if not haunted, by his upcoming book, "Evidence of Things Not Seen," a nonfiction account of the Atlanta child murders. Baldwin wrote an article on the mass slayings for the December 1981 Playboy, and afterwards was persuaded to expand it into a book that will be published by McGraw-Hill at the end of the year. For the past four years, he's been in and out of Atlanta, talking to lawyers, mothers of the slain youths and city officials. He couldn't interview convicted murderer Wayne B. Williams, because the case is on appeal. But he talked with Williams' parents. His research files, he says, with an elegant gesture toward the ceiling, are "taller than you are."

He pauses and his hand floats back down to the starched linen tablecloth. "Two years from now, ten years from now, I'll be able to be very intelligent about it. Right now, it's very hard for me to talk about it," he says in a hush that mounts to an occasional crescendo, then subsides again--a kind of rockabye lull not unlike that of the surf. "Although this must be said: Once I was asked to do it, it occurred to me that I might have had to do it anyway. Once I started, I couldn't duck it . . . I went to Atlanta, where I'd been before in 1957 and which I love very much, in fact, and which, to put it very simply, had changed a lot since I was there for the first time. Changed in some ways, not in others. Like the country itself. And it took me back to, well . . . a lot of my friends didn't die in bed . . . It carried me back to . . . to an anguish which, I want to say, I'm trying to forget. Still you had to live through it. I'm talking about the slaughter of Medgar Evers, the death of Malcolm X, the death of Martin Luther King and many, many others. It opened up bad wounds, which had never really been closed."

His voice expires and in the stillness of a room marred only by the tinkling of forks against fine china, his features are gravely immobile. "All those kids could be my kids," he says. "They are my kids."

Baldwin has one of the world's great faces, etched with the hieroglyphics of sadness, and yet for all the pain it suggests, still possessed of a certain elfin charm. His hair is touched with an aureole of white and his forehead is deeply furrowed. But when he laughs--a great, expansive laugh--it is not simply to reveal the broad gap between his front teeth, but the eternal boy in the world-weary man. The face is like a moody landscape that seems lit by lightning, not just the periodic flashes of a photographer's camera. Baldwin is not unaware of its inherent theatricality. Under the mask of tragedy, Puck manages to peep through.

He wrote "The Amen Corner" 30 years ago in Paris, just to "see if I could write a play." Its central character is a woman preacher in Harlem who turned to the Lord with a vengeance, verging on fanaticism, to fill the void left by her errant husband, a jazz musician. His reappearance many years later, broken and dying, throws her whole life into question, and she finds herself battling to save her church, her son and the rigorous sense of righteousness that has allowed her to survive.

The premiere took place at Howard University in 1954, where Baldwin rewrote much of it in seven days. "That great black poet Sterling Brown shepherded me through it, trusted the parts of the text I didn't trust. It was an extraordinary time in my life, working with actors, a director. I hadn't realized that you could say many things in a play with silence . . . After that, it was packed away in my trunk for nine years. I never thought I'd see it again. But it was picked up in Hollywood in 1964 by Frank Silvera and ran for a year there, which can be considered its first real resurrection. It's been on the road ever since, at theater festivals in Europe. All sorts of small companies I don't even know about do it here and there."

Whatever proprietary attitude he might have once nurtured toward the play, he has long since relinquished. His input this time around is mostly advisory. Philip Rose, Peter Udell and Garry Sherman--the triumvirate responsible for "Purlie" and "Shenandoah," among others--are shaping the musical's fortunes. Baldwin doesn't even pretend to know what the budget is. He will be here for the opening and he will probably attend the Broadway opening at the Nederlander Theater Nov. 7. But, he says, shrugging with lofty magnificence, "It is no longer my play. I mean, time has taken it over--time I never expected to live to see. There's something quite strange about being confronted with it so many years later. In a sense, the audiences that have claimed it know more about it than I do."

The waiter uncorks a bottle of Chateau Mon Bousquet, 1976, and lays it delicately to rest in a wicker basket so it can "breathe." For all his years in France, starting in 1948 with self-imposed flight from the horrors of his Harlem adolescence, Baldwin admits he knows nothing about wine. However, the vintage--the bicentennial year--strikes him as "a very good omen." His large basset eyes betray a sense of playful irony that is lost on the waiter.

The adaptors of "Amen Corner" have altered Baldwin's ending somewhat, attenuating its sense of tragedy. But Baldwin believes that the preacher woman's central dilemma--"how to treat her husband and son as men and at the same time protect them from the bloody consequences of being a man in this society"--is as valid now as ever. "In spite of all the American pretensions of progress, in spite of all that's happened in the last several years," he says, when he once again decides to speak, "nothing has changed enough to alter the trap against which the people in 'Amen Corner' are struggling. Nothing in daily American life from 1953 until now alters the dimensions of that trap. Oh, things are always changing. But the change is never what you thought it would be . . . Contrary to my reputation, I am not a revolutionary. I'm not romantic enough. To me, the word revolution means only . . . well, I take the key from the movement of the wheel. It revolves. It stops where it started. What happens is that human energy forces a change in the world. But no one is quite sure where it goes. No one quite knows what it means. There's no guarantee anything is going to be better . . . I do know people cannot endure their misery forever. I do know we're in terrible trouble.

"After all, millions and millions of people have believed and still believe in the American dream. Something very serious happens when it is repudiated by the presumed authors of it. The price for a new world, as far as Americans are concerned, is an examination of their own identities, a genuine examination of their own history, which is not going to happen tomorrow, if it ever happens. We talk about the 1960s as an era of liberation as if it were the middle ages. Some things became fashionable--what we call homosexuality is one of them--without being understood, without being, above all, confronted . . . I don't think the real attitudes of Americans toward all their anathemas, their pariahs, really change."

His thoughts on the subject are momentarily spent. "I don't want to talk about the play," he says. "It's lasted longer than I thought it would . . . If the musical works, it works. If it doesn't, I'm not worried about that at all. Musicals do crash. To tell you the truth, the only thing that concerns me about it is my cast, a beautiful cast. If I write a novel or a poem or an essay, it's only me who can be in trouble. Whatever happens, happens only to Jimmy Baldwin. But a play or movie involves so many other people. There's a certain terror involved in that."

For a man whose reputation has been built on the searing quality of his prose and the unflinching observations in such books as "The Fire Next Time," "Nobody Knows My Name," "Another Country" and "Giovanni's Room," Baldwin is oddly gentle, even shy. He has an abiding fear of speaking rashly. "Every time I speak, I'm aware that I've got to tell the truth," he explains. "And I've got to be aware of what will be made of the attempt. It's a little like writing. Inevitably you're taking a chance. But . . . voila ."

He seems, however, to derive a sly pleasure from the paradoxical image he presents over dinner. An American writer who found his voice in exile in France, he professes no comprehension of such European concepts as "existentialism," "schizophrenia" or "psyche." "I'm not a European, I'm an American," he maintains mischievously, dismissing the terms with another bird-like swoop of the hand.

For all his Cassandra-like visions of a white America, unable to shake free its racist myths and fantasies and veering toward some awful holocaust, he claims stoutly, "I am not a pessimist. I don't want to be put in the position, once again, of crying woe. Then I become a doom-monger. I have no right to depair. What's despair, anyway?"

During the civil rights campaign, he was thrust into the forefront as a public personality, pointing a finger at the malingering national conscience, but he says now, "I never intended to become a public figure" and he gives some evidence of being acutely uncomfortable in the role. The writer in him clamors for the seclusion of the French village, but duty summons him repeatedly to New York. "I have a typewriter in France and responsibilities here," he says.

Although he accompanied Martin Luther King 20 years ago on his famous March on Washington and wears a wristwatch with King's face on the dial and the letters spelling "I HAVE A DREAM" where the numbers usually are, he did not participate in last month's 20th anniversary march.

"How can I put this? A lot of my friends were there . . . Maybe I would have been if my schedule had allowed it," he reflects. "I don't think I can address that question for the public. I suppose that one feels one has to find another way to do it. Perhaps that was my hesitation. Perhaps I was thinking of Martin. Perhaps I could not imagine, and I am speaking for myself, that petitioning this government with a list of grievances was not meaningless. I don't believe this administration has the remotest ability to hear any petition. Does that make sense to you?"

He pokes at one of the three-minute lamb chops, isolated by the mandates of nouvelle cuisine in the vast whiteness of his plate.

"I didn't go to France, by the way," he volunteers. "I simply left America. I couldn't go to Africa. There was no Africa then. I might have gone to Israel. I thought of it. I ended up in France by putting my finger on a map, actually. I had friends in France. Well, I thought I did. Put it that way. In any case, what I wanted to do was find out who I was, not what I was. And actually, what you find out in France is that if you are not French, you do not exist. That was exactly what I wanted. To be left alone. If I could make it, I could make it. So much the better. If I couldn't, so much the worse. But I wanted to leave it up to me . . . I wanted to find out if what was happening to me was happening because I was black or because I was Jimmy. And not go through my life confusing the two. I had to find out."

What he found out was that he was a writer whose prose was imprinted with the cadence of the church and the rhythms of the musicians who befriended him in the days when he was merely trying to stay afloat in Harlem. And he found out what his role was.

"I think the artist is a disturber of the peace," he explains, fingering the gold medallion that hangs in the open expanse of his white shirt. "He is produced by the people, because the people need him. The people may not like him, they may stone him, but they need him. His responsibility is to bear witness to and for the people who produced him. When the chips are down, that thought saves me on some level from the nightmare of show business, from the nightmare of thinking that my talent belongs to me. It doesn't. That's why it's called a gift."

He looks off across the empty room. The German diners have departed and the waiters look forlorn, their professional obsequiousness on hold.

"You have to bear in mind that everybody wants an artist on the wall or on the library shelf, but nobody wants him in the house," Baldwin says. "I'm worth much more dead than alive. That doesn't bother me. It did once. It doesn't any more."