Anyone in the public eye, whether it be a movie star, a television personality, a politician or even a columnist, has a better idea than most people of what happened in front of the Washington Hilton Monday afternoon.

Somewhere out in this country are sick people who, though complete strangers, harbor bitter grievances against well-known individuals who have never done them any harm. But for some reason, they have decided that a particular person is responsible for their pain.

The mail arrives, and among the letters are the anonymous scrawls of anger and hate. The scrawls can be threatening, or they can make no sense at all. You tend to laugh them off, because you don't want to admit to yourself that somebody out there has chosen you as the target for his discontent.

The letters are either thrown into the wastebasket, or placed in the increasingly large "nut file" that you've built up over the years. Sometimes the mail continues for months and even years. Other times one letter is sufficient to relieve the person of whatever is bothering him.

The hate and the anger and the frustration are not only transmitted through the mail, but also over the telephone. The stranger tells you what you have allegedly done to him and asks you what you are going to do about it.

The trick is to talk calmly and assure him that whatever his grievance is, you will look into it. You try to persuade him that you are not responsible for whatever is hurting him, and you end the conversation as quietly and gently as you possibly can.

Fortunately, very few people act out their fantasies of "getting even" with the person they have chosen as the one who is tormenting them.

But every once in a while someone decides he or she must take action.

The most obvious person in this country to take action against is the president of the United States. It doesn't matter what party the president belongs to, or what his political philosophy is. The stranger has decided to have his day in the sun.

The problem of obtaining a gun to carry out the fantasy is no problem. In almost any state you can buy a weapon. You can get one for as little as $20 or one for $200, and in many places you can buy a gun with no questions asked.

Stalking a president is also no problem in a country where presidents mingle with the people. The opportunity to fire the gun is a matter of luck and daring. No Secret Service or umbrella of police personnel can protect a person from the stranger who is intent on shooting someone.

And sometimes the deed is carried out, as it was Monday, when a smiling president waved to a friendly crowd on the streets of the capital of the United States.

But presidents are not the only targets for the sick people who walk the land. The victims can also be John Lennon or a little black child in Atlanta.

And every time it happens, the American people rise up in anger and say "What can we do?"

Stop the sale of handguns? It might be a good beginning, but the gun lobby will never let it happen. Lock up every sick person in the country? It can't and shouldn't be done.

The truth of the matter is that there is very little that can be done.

The brooding stranger, who dreams of taking his revenge, is always amongst us. But until the gun is fired, nobody knows his name.