ONCE THE SHOTS were fired on Monday, we all knew exactly what to do. A Secret Service officer put one arm around the president's waist, the other on his back, bent him double and stuffed him into the armored limousine. Other security officers forced John Hinckley to the ground and covered his face with a suit jacket. The television cameramen, despite the gunfire, the screams and the confusion, kept their hands steady as they filmed the action.

Within minutes, White House aide Lyn Nofzinger knew that he had to step in for the wounded Jim Brady. The television networks knew they had to preempt the afternoon soap operas. Every newspaper editor in the country mentally planned his front page with the lead story on the shooting and the sidebars on the identity of the gunman, the whereabouts of George Bush, the situation at the White House and the scene at the hospital.

No one knew his part better than Ronald Reagan. He gave the performance of his life as the wounded president. From the final wave before the shots were fired to the way he managed to walk into George Washington University Hospital, it was all perfect. It did't matter that the joke he stole from W.C. Fields ("On the whole, I'd rather be in Philadelphia") can be found on page 951 of Bartlett's. This kind of gritty humor was what we wanted to hear.

We didn't need a network commentator to draw historical parallels for us. Instantly we remembered Dallas, Jack Ruby, Sirhan Sirhan and Sarah Jane Moore. Many of us even knew that since 1840 every president elected in a year ending in zero had died in office.

Even before the alleged gunman had an identity, we could all draw his psychic portrait. We could see the hollow eyes, imagine his psychotic ramblings and picture the barren motel room in Denver with the wrappers from discarded Big Macs.

On Tuesday we learned that John Hinckley seems to have been influenced by the film, "Taxi Driver" which was loosely based on Arthur Bremer, the man who shot George Wallace. Hinckley could have just as easily been affected by the silent drifter who assassinates the country music star at the end of Robert Altman's "nashville."

From Bremer to Hollywood to Jodie Foster to Hinckley. What can you say?

Nothing. That, perhaps, is the ultimate horror of Ronald Reagan being shot. There's nothing left to say. We've said it all a half a dozen times since 1963.

America is a nation built on rationality. Our Protestant ethic dictates that even the most tragic events should have some enduring lessons, some lasting meaning.

Sure you can draw morals, but they are as familiar as a sermon on the Ten Commandments.

Americans are a violent people. Handguns should be controllled. The National Rifle Association is wrong. The Secret Service has an impossible task. There should be better communication between local law enforcement agencies and the Secret Service. Our political system depends on a president's being able to meet the electorate. The government should have a better system of crisis management in an emergency. Political assassination is rare in Western Europe. Television makes violence trivial. Deranged criminals become celebrities.

Ten pieces to fill a newspaper opinion section on a Sunday. But we've read them all so often that we could recite them in our sleep. We've gotten good at this. A lone nut fires at a president and we know what to do, what to say, what to think. We've been over this ground before.

Sportswriters with the excess of spleen that comes with their profession have attacked the NCAA for going on with business as usual. I'll confess that I watched Monday night's basketball game between Indiana and North Carolina.

I knew that there are far more important things in life than the NCAA basketball championship. I suffered with the rest of the nation while Reagan was in surgery. I grieve for all those who considered Jim Brady a friend. My heart goes out to the Secret Service officer and the D.C. policeman who were wounded in the line of duty.

But by 8:30 on Monday night, I knew that there was almost nothing left to say. How many times could we watch the filmed replay of the shooting? How many times could we draw the obvious conclusions about guns and lone nuts and a nation of 230 million? For how long could we watch television anchormen try to match Walter Cronkite's performance on that November day in 1963?

In all likelihood in the days ahead, someone will try to claim that John Hinckley was just the front man for some hidden conspiracy. It doesn't matter that the evidence will be implausible or that hundreds of people will be accused of participating in a "coverup." What's important is the psychological need to believe that the tragic events of Monday afternoon fit into some rational pattern.

Lone nuts like Arthur Bremer and Sirhan Sirhan are frightening.They remind us that we can all be victims of random and purposeless events, that history can be altered by a few seconds of insane violence.

Life goes on. Even Jim Brady, who death was announced on television on Monday, seems to be recovering. On Tuesday, President Reagan signed a bill into law from his hospital bed. The White House backbiting against Alexander Haig continues. Pollsters are already calculating the political benefits of surviving an assassination attempt. Indiana won the national basketball championship. "Ordinary People" won the Academy Award for the best picture one day late.

Ultimately, what is both reassuring and horrifying about the shootings at the Hilton is how ordinary it all seems.

It is reassuring that Monday reminds us that we have the most stable political system in the world. A gunman wounds the president and the government goes on automatic pilot. There are no crowds in the streets, no ugly demonstrations, just small groups of Americans gathered around televisions and radios participating in the shared drama of national tragedy.

But this sense of ordinariness is also horrifying. Sixty-nine days after he takes the oath of office, Ronald Reagan is shot. Even the leaders of banana republics have a more secure existence than that.

Writing about Nazi mass murdered Adolf Eichmann, Hannah Arendt coined the phrase, "the banality of evil." In contemporary America it is tragedy and attempted assassination that have become banal.

There's nothing more to say.