HE IS SLIGHT and wary-eyed, and with his fine hair leaning over his forehead he looks a little like Brando playing Napoleon. He sits as if the sofa doesn't fit. He can see, through the wall-sized window, Central Park sweeping away to the East Side skyline. There is no music.

"I'm playing baseball this afternoon. It's my son's birthday". He looks down, curling his fingers. "I always have to think about something that might hurt my hands."

Paul Simon is 38. He looks younger. He looks vulnerable. He looks like a man who's always had to think, a man who has broken his talent to the bridle of his art. And sometimes, perhaps, it has taken him for a ride.

It's been five years since "Still Crazy After All These Years". For the past three, Simon has been laboring over his first film script and its soundtrack. Now the album's first single, "Late in the Evening," is shivering its maracas all over the airwaves. The movie, "One Trick Pony," has just opened in the top markets (it comes to Washington next week), and Simon is out on his first U.S. tour since 1975.

So 20 minutes into his New York opening concert, Simon fluffs his lines.

"I went straight out on stage without warming up and everything was a little up-tempo and I was pushing my voice and improvising -- and all of a sudden I started listening to the lyrics. I don't mean to sound like I think they're great, but some of those songs are six, seven years old and I'm usually paying attention to the melody or playing with the rhythm . . . and all of a sudden I thought, This is my life. That was Peggy, I remember that day, that was so-and-so. I really felt those things."

For 20 years, witty wry and syncopated, Paul Simon has been paring his songs into curls from semi-autobiographical apples, cutting closer and closer to the core. From a self-conscious '60s visionary -- "The words of the prophets are written on the subway walls" -- he was evolved into a deft chronicler of American life and its constraints: "I know a man, he lives in my home town/He wears his passion for his woman like a thorny crown."

"I think the later songs are vastly superior to the early material," he says now, but without embarrassment. "They were big hits, but some of the early stuff, 'Sounds of Silence' . . . I didn'nt really know what I was doing. They just came naturally."

His lyrics no longer spin at their whim, and nowadays he wonders if anyone is listening. "There Goes Rhymin' Simon" sold only 1.35 million copies. "Still Crazy" won him two Grammys, but its sales stayed under 2 million - - respectable numbers but a long way down from the 8 million copies of "Bridge Over Troubled Water." %t"The newer songs are better, and I think people would like them better [than the old Simon and Garfunkel hits] if they listened to them more than once. But I don't think we -- Americans -- are willing to do that. You hear something once, and if you don't like it, you don't listen again."

The room has settled itself around him, unobtrusively elegant, a little wary like its owner: blond wood floors, white walls, off-white furniture, all frame for the baronial view. The piano and the stereo equipment are off to either side. Even the Scottie is off-white and comfortably in need of a bath. %tI went to see the new Woody Allen movie 'Stardust Memories' the other night, and there's a part where he talks to these extraterrestrial beings or whatever about the meaning of life. And they say, 'You wanna help mankind? Write funnier jokes.'

"Well, people are always doing that to me. I'm trying to say something important in a new way, and I'm playing with the rhythm and I'm undercutting this line with some ironic harmony, and people say to me, 'Why don't you write more happy songs?' You know, like 'Cecilia' . . . 'Red Rubber Ball.' They just want to hum along.

"But I do the same thing. I know there's a lot of stuff packed into 'Stardust Memories' that I could get if I saw it another time, but I also know I probably won't see it again because it's kind of sad. I'm writing serious, and I want Woody to be funny."

Everyone wants everyone else to stay the same. Sing the songs, write the jokes, play the games. Heroes aren't supposed to grow old. Where have you gone, Joe DiMaggio? Neither is a pop star. The Beach Boys are surfing in an implacably endless summer. The artist, who wants to learn, to push himself, risks pushing away his audience.

They are an interesting paid, Paul Simon and Woody Allen. Of similar age and disposition, they stand off at the edge of the self-exposure craze like chaperones at a petting zoo.

Rueful, reckoning, they have written their private histories into the passages of American life. A lover at a time, a loneliness at a time, but never as simply from real-life as they made it sound. It's a kind of conjuring trick: Now you see me, now you don't. Allen created Alvy Singer in his own image, and now Simon has Jonah Levin, the protagonist of his new movie, "One Trick Pony." He looks so easy, he looks so clean, He looks like God's immaculate machine. And he makes me think about all these extra moves I make, All this herky-jerky motion And the bag of tricks it takes To get me through my working day.

"One-Trick Pony" began as an artistic isometric, the stretching of new writing muscles. "I figured I could either try a Broadway musical or a movie, and I decided making a movie would be more like making a record. You finish a take, then you can do another or three or however many and then edit it the way you want to."

Jonah Levin is a pop singer-composer, a one-hit star measuring out his life in plastic coffee spoons. He is the pony of the title, turning his one trick and struggling with the rest. His wife is divorcing him. She and their son live in a fancy apartment, a holdover from more prosperous times; Levin lives in a basement.

There are, as always, pieces of Paul in the play; the two-man baseball game with his son, the tensions between marriage and music (Simon and Peggy Harper were divorced in 1975), between art and commercialism. "I wrote about the things I knew," he says. "But I was never a touring musician like Jonah. He's a composite of any number of performers I've known."

The music was finished about halfway into the screenplay. Simon hadn't originally planned the movie as a vehicle for himself, had even spoken with Richard Dreyfuss about starring in it, but "I knew we couldn't have some other guy on screen opening his mouth and singing with my voice. People would laugh."

When the script was finished. Simon went to Warner Bros. and 20th Century-Fox and said, "Here's the screenplay, here's the music, call me tomorrow." Both said yes. Simon went with Warner Bros. because he is already under contract to their record division. (He left CBS in 1978 for a reported $10-15 million three-album deal). Warner Bros. gave him virtually complete artistic control - his business manager served as producer and Simon hand-picked the director, Robert M. Young of "Short Eves" -final cut rights and a $6-7 million budget, which he exceeded by about a million. The filming consumed a month in Cleveland and five more in New York.

"I studied every part in the script as many ways as I could, so I could help if someone said, 'Hey, this doesn't work for me.' I had to listen to the dialogue as if I'd never heard it before. The first couple of months were fun . . . The last weeks I had to make myself do it."

All during the filming, Simon and the director refigured and reworked. "I wrote very minimal stage directions, like 'Jonah Marion are in the kitchen.' I really went into the movie without knowing much about it. It wasn't until we were into the editing process that I set up a color chart: one color for the high emotional scenes, one for musical numbers, one for the light stuff and one for exposition.

"I charted the progress of the movie that way" -- he blocks off sections of air into a huge graph -- "and I began to understand the shape of a movie, how it balances. You can see where you need a lighter scene, a short piece here. If I did another movie, I'd know all that."

But he's not really sure he wants to make another film. It was something new to master.

"There's a word for it. Opsimathy. I looked it up the other day. It means learning late in life." He smiles. I am older than I once was, Younger than I'll be, That's not unusual. No, it isn't strange; After changes upon changes We are more or less the same. After changes, we are more or less the same.

Paul Simon is a New York borough boy, He and Art Garfunkel went to Forest Hills High, cut a record at 15 (as "Tom and Jerry") called "Hey Schoolgirl" that got them as far as "American Bandstand", but none of the followups floated.

In 1964 the partnership reformed and Columbia released "Wednesday Morning, 3 AM" from which producer Tom Wilson pulled "Sounds of Silence". Wilson grafted on an electric guitar, bass and drums and sent the single out to No. 1. (The song is still stronger when Simon plays it with just the guitar, as he does live.) Simon and Garfunkel had a series of hits over the next several years, but Simon's soundtrack for "The Graduate" was a stunning experiment in conceptual scoring, accounting for two of Simon's 21 Grammys.

"Bridge over Troubled Waters" won four grammys, sold 8 million album copies and marked the official end of the partnership, although they have appeared and recorded together in bits and pieces since. But it is in his solo albums, such as "There Goes Rhymin' Simon" and "Still Crazy", that Simon began to produce his best work.

His 1978 prime-time special won an Emmy (but it did not, as he has often pointed out, win the night's ratings). His only movie appearance, prior to "One-Trick Pony", was as a Hollywood producer in "Annie Hall".

These days Simon shares his apartment with actress Carrie Fisher and sometimes with 8-year-old Harper. He is touring for six weeks behind the movie, a tour so short it will fall a couple hundred thousand dollars into the hole, a tour short enough to be bearable.

"The bad nights are the ones where you wake up in the middle of the night and say, 'Where's Carrie? What town is this? What was the sound system like? It was an arena -- it's Detroit, Oh, God, I'm in Detroit at 3 o'clock in the morning!'

"I always say, This tour is the last." Once I was crazy, and my ace in the hole Was I knew I was crazy, So I never lost my self-control. I'd just walk in the middle of the road, I'd sleep in the middle of the bed. I'd stop in the middle of a sentence, And the voice in the middle of my head Said, "Hey, Junior, where you been so long? Don't you know me? I'm your ace in the hole."

The thing is, Paul Simon never was exactly who we thought he was, never was that easy. He had an irony, a melancholy that set him apart. Look around, leaves are brown. All my words come back to me. When something goes wrong, I'm the first to admit it -- the first to admit it, the last one to know. He was always quietly at odds with the violins: Nothing but the dead and dying back in my little town. His album is collections of contradictions waiting to be decoded.

His music has always been off the beaten tracks, too; gospelized, jazzy, Latin, literate. For this tour (which will not include Washington) as for the last, he has added the Jesse Dixon singers, a hallelujah quartet who knock the last too-solemn stuffing out of a gospelized "Bridge over Troubled Waters." It is a street-smart show, with a saaay horn sectin wailing and the percussion playing hob with the time signatures. There's a fire escape painted on the scrim and a basketball key angled on the floor.

The Palladium is an old rococo moviehouse, with Aphrodites and lute-playing cherubim and columns and draperies -- the gilding of the silly. Deceptively solid in baseball jacket and faded jeans, guitar butted against his hip, Simon takes a step into the light.

"You know, I grew up in Queens [cheers]. It used to be kinda unhip to be from Queens. People always made jokes about it, I never really knew why. I lived in one of those attached houses . . . I remember when there was no Long Island Expressway [more cheers], when you could see across the fields all the way to where the World's Fair was.

"Well, it's turned around, and now it's hip to say you're from Queens. But my point is this: You just keep on bein' who you are, and sooner or later, they'll get it."