ON THE PHONE from New York it's Steven Seymour, the interpreter. He's telling how it happened. He's telling how he took President Carter's airport remarks and made them memorable, how he had the President carnally desiring the Poles, how he had him leaving America forever, how he chirped away in Polish to an audience that couldn't believe its ears. He felt just wonderful about the whole thing. "I though I had done a hell of a job," he said.

He hadn't. He didn't. It was awful. He knows that now. For a while, he didn't know a thing. For a while, he just traveled in this wonderful cocoon - all the time and palaces and the motorcades and the hotel rooms and that sort of thing. Not a hint, you understand. Not a word until he got to the airport to go home. Then a correspondent came up to him and asked him if he was Steven Seymour - the Steven Seymour. Then he knew.

"He told me. That was news to me and needless to say I was very apprehensive. I arrived in New York and went right to sleep. The following morning, when I called by parents, they broke the story to me." His parents' New Year's was ruined. His friends felt awful. Seymour himself was upset, chagrined, mystified - famous, for crying out loud. It was the holiday. There was no news. There was Steve Seymour and the Sex Pistols.

On the phone from New York, the voice has an accent. This was supposed to be an interview conducted in person, but Seymour has broken from the gate. He has talked to other newspapers, he tells me, and so now he is talking to me on the phone. On the phone he says the accent is Russian, that Russia is where he was born but that he spent five years in Poland - four years of high school and one year at Warsaw U. He is 31 years old, a bachelor, usually a Russian interpretar but also, he insists, fluent in Polish.

Steve Seymour - what theories we had about you. Steve Seymour - what explanation we had for how it happened. Steve Seymour, you captured our imagination. You were the guy who left the house that morning and turned to your wife saying, "Don't worry, honey, I'll wing it." Or you were us in a high school language class, on our feet, unprepared, fear bringing the sweat out of the small of the back. It's the French class. You start to speak. Spanish comes out. Who can explain it? Who can forget it? Steve Seymour - every person who ever froze, who faced the audience and collapsed, who went somewhere thinking you would think of something but who arrived thinking of nothing. Steve Seymour, how did it happen?

"First of all. I didn't have the text of that address until the last moment. I left Washington on the 27th December and arrived in Warsaw the following day. Before going there, I had been briefed in Washington on the 23d of December, when I got background information. I was hoping then for the text and then again on the 27th and then I waited in Warsaw.

"On the evening of the arrival, the President arrived late. The speech was made around 11. I came to the airport a little after 8 and I was told that the text would be given to me when Air Force One landed. Now between 8 and the time when I started, there were no facilities for me. I had to stand outdoors in the snow and the rain. It was very cold and I was frozen to the point where I was shivering."

Now understand. Steve Seymour is now all right. He is working once again for the State Department, and he has gone over that night many times in his head. It had been a year since he last translated Polish and that, to tell the truth, was his only Polish translating job - trade negotiations for the Commerce Department. His beat, so to speak, is Russion, not Polish, and now he is waiting for the text and it does not come. It is cold and the television technicians are pushing him around and everywhere he moves he is blocking their lights or their camera angles. He is pushed around by the police and the soldiers and he steps into puddles and he starts to get a bit nervous - not scared, mind you, but what he terms "a healthy respect for the situation."

Now the music starts and the plane comes out of the black sky and now there is bustle and rustle and Steve Seymour who nobody has noticed prepares to do his thing. The big plane lands and he gets the text and he gets 15 minutes, he says, to read it - "improvising and groping," he calls it. "Everything kept moving. The soldiers kept marching and the music was playing and I kept being moved. I was either on the line of the camera or something."

Now the music stops and the soldiers come to attention and the President of the United States is ready to speak. Later Seymour would say that there is no explaining what happened, that it must have been the effect to the cold and the rain and the tension. And later he would point out that anything having to do with language involves the subconscious and things we do not understand. But that was all later, for at the moment the man night is about to go to work. The President speaks and then Seymour speaks and then a funny thing happens.

Everyone finally notices Steven Seymour.