Is there a journalist in this fair city Who does not dream like Walter Mitty Of finding underneath Key Bridge A secret file on Calvin Coolidge?

ON ONE early day in the current "sting" scandel, three front-page stories in The Washington Post were of the according-to-unnamed-sources genre. The magnitude of the leakage has accordingly been a heated conversational topic, as heated as the subject of entrapment, provoking Nicholas Lemann to observe in this section last week that such talk might distract our attention from "the simple horror of what a number of congressmen apparently did."

Lemann's point, though a good one, did not keep Attorney General Benjamin Civiletti himself from providing distraction in the form of an investigation of the leakage. And The Post's own editorial writers then preceeded to distract us further by raising the issue of the role of the press: "The press has been at once too aggressive in airing unproven charges and too reticent about tracking down their purpose and their sources." I was personally more distracted by this editorial observation than by any of the other distractions.

Were The Post editors chiding their own kind for not knowing their own sources? I have trouble understanding the remark (the word "reticent" is curious, for instance, rather than, say, "lazy"), having always innocently assumed that in the top secret files of all investigative organizations the unnamed sources are either named or weightily speculated about. Perhaps The Post's editors were saying that this particular "sting" leakage was a new phenomenon even in their experience. Perhaps not. Anyway, the furor suggests to me that there may well be horrors floating about equal to the congressional horror.

Lemann wanted to concentrate upon putting the congress in order, but there remains the American house to be put in order, a house that happens to include entrapers, leakers and journalists. In the end, who will escape whipping?

In asking us to focus on Congress, Lemann was at pains to point out that members of Congress are particularly vulnerable to temptation from big money. Obviously they are, in the sense that temptation often comes their way. (Many of us could stand out in the street daily waiting for a bribe, yet remain wholly, if sullenly, pure.)

Yet congressmen, though they may be particulary vulverable, are not peculiarly so. All positions of power in our country, in the public or private sector, are vulnerable, including positions in the FBI, including positions in the media. And not only are all our power holders vulnerable; they also have all received pretty much the same conditioning in self-aggrandizement -- that is, in giving in to the making of almost any kind of buck. For, reversing old Emersonian idealism, the making of a buck has become transcendental in our time, transcendental in the sense that it rolls unimpeded through all things. If we are to have moral rearmament on Capitol Hill we may well have to look for our congressmen in some other country; and if the stingers and leakers and journalists are to lead the rearmament they had first best arm themselves against the possibility of a "sting." Which brings me back to the business of sources.

Moral journalists indignation about the preservation of sources should be tempered -- and I suppose is tempered by the prudent -- with an active awareness of the temptations lying about. For every easy assertion that in the protection of sources lies the strength of a free press (as well as the capacity to uncover crooks and therefore assist in our national purification), the reporter needs to heed a seperate but equal assertion, that in the concealment of sources lies deceit or potential deceit, and splendid opportunities for payoffs.

Of course I have no inside information whatsoever, and will be innocently shocked if any of the "sting" stories published lately are found to have involved payoffs. I am merely thinking of Murphy's Law, that if anything can go wrong, it will, and finding little justification around me for supposing that journalists are less likely to go wrong than congressmen.

Is there a solution? I suppose that for journalists to wear sackcloth would help. Or perhaps they could go off and read lots of Emerson, thereby growing more moral daily, less vulnerable to what he called scornfully, "vulgar prospoerity." But really it would be much simpler for reporters to start their careers with respect -- a respect they do not have now -- for the fusty scholarly rules for acknowledging a source. To acknowledge it, to assess its reliability and to give a reader sufficient information about it to enable the reader to make his own assessment of it -- these are cumbersome requirements and obviously have to be streamlined for the daily press; but they do not, I am convinced, have to be denied or ignored to produce intelligent investigative reporting.

The discomforts and of course possible dangers to a source of being revealed must be matched with the dangers to the whole reportorial profession of the source's not being revealed, and in any such matching I can only think that the freedom edge, the moral edge, the truth edge will go to open revelation every time. Indeed the fundamental premise of our most diligent investigative reporters is that they do what they do to give us openness, to give us all . Part of that all is surely the investigative process itself.

Nor are freedom, morality and truth -- those grand issues -- the only issues here. There is also the small matter of humanity, or lack thereof. A secret source is an informer, a sort of spy. The Soviet Union makes heroes of their spies, and names elementary schools after them, but in our country -- and in peacetime, while serving or reporting on our own government -- a spy is not so redily enshrined. An informer's motives, in Washington in 1980, are bound to be somehow connected with malice, if not greed. And that there is a ready market for informers here, and that there are ample numbers of insiders ready to enter that market as well as journalists willing to help them, should indicate something to us about our whole climate, should indicate among other things that the enormity of the act of betrayal is little thought of in this town.

For betrayal is what is involved, betrayal of some kind, every time an informer, even with piety in his heart, speaks. Our culture's present moral callousness about betrayal is to me a genuine first-class horror.