"I KNEW 'they' would try" -- it was one of the first broadcast responses of a bystander when the news of the attempt on Mr. Reagan's life became known. Our mind (we are all so abysmally accustomed to, even practiced in these things) raced back to the same kind of certainties that were expressed when John Kennedy was killed in Dallas and George Wallace shot in Maryland: they -- we all thought we knew who they must be in the political context of the moment. This, it seems to us, is one of the first things to be avoided this time. We don't know at this writing much about the suspect who is being held for these crimes. But everything we do know at the moment points to the same vicious, violent derangement that has brought the country such an excess of grief of this kind in the past two decades.

If this is the case, it will also reaffirm the terrible truth that there are limits on the kind of protection -- insulation, really -- that can be afforded a president, unless it is intended to cripple completely his ability to lead. Certainly the Secret Service precautions and the security generally of the president will need to be reexamined in relation to this terrible event. And it is surely possible that some fault lay in the character of those protections, that things will need to be tightened up. But it is also true and very important to remember that there is a point beyond which these protections cannot go.

Ronald Reagan has in fact rather altered the conception of the president's role since he took office. His idea of leadership -- and there is something to be said for this particular form -- clearly has a lot to do with persuasion, ceremony, a kind of embassy to his constituents and to the other branches and levels of government. He is not the man who wants to make every technical judgment or decision. He is the man who wants to bring the country with him on a broad front of policy changes, and he intends to do this by means of a great deal of mingling with the people who must help him make the changes and with those whose opinion and consent must somehow validate them. You do not have to buy the content of Mr. Reagan's program to accept this concept of presidential leadership and to accept the obvious corollary that such a president will never be completely outside of the danger of a criminal's bullet.

But none of this makes the ordeal any less outrageous or heartbreaking. How many times must public figures, their families, the rest of us endure this? How many innocent victims like Jim Brady must there be? How many brave policemen and Secret Service agents like Officer Delahanty and Agent McCarthy must be shot in these ugly proceedings? Has everything been done that must be done to limit the opportunities as much as possible? We will not believe that it has been until those damnable firearms have been put out of the reach of every criminal and potential criminal who wants one -- to whom they are accessible now. But we do not move from this to some general complaint about the society itself or to those old and spurious complaints about how we are a violent or aggressive people collectively. The caption on this dreadful picture is not that Americans as a nation or a people are violent or weak, but that some among us are -- and are armed.