Out of the incoherent welter of national life, there emerges as practically everybody's candidate for Public Issue No. 1 a thing called leadership. But what is that?

Well, one way to define the genuine article is to finger the bogus competition. The more so as a huge national audience regularly mistakes counterfeits for coin of the realm, myths for reality.

Leadership myths generally spring from the illusion of identity between private and public qualities. In keeping with that quaint conceit, individual virtues are taking to be some kind of infallible guide to leadership capabilities.

Thus a candidate's relationship with his wife is supposed to matter immensely. And with his mother. And with his God.

Achievement follows private life as the next supposedly infalible index. Would-be leaders have to excel in brains, sports, looks, glamor, reading ability and diligence. They write books and run races. They do everything except what most other Americans do -- which is to be ordinary.

Most important of all is a myth about command decisions. Leadership is said to assert itself in crisis, to discern the true course when all is confusion, to bark the orders that cause the rest of us to turn around, and to bring us safely through shipwrecks to salvation. The model is Lincoln in the lonely watches of the night, not to mention Moses leading his people to the Promised Land.

In fact, however, leaders are no more individuals writ large than a compound substance is the mere sum of its atoms. An atom of carbon is common to both a lump of coal and a diamond. What makes the difference -- what determines why one burns and the other sparkles -- is the principle of agglommeration. Wht counts is not in each individual atom but how they come together.

Leaders are not loners either. They work against a background of interests and institutions and a climate of opinion. What is decisive is how one fits together with others.

Virtue, especially preeminent virtue, is not a quality of great importance. Herbert Hoover was an exceptionally virtuous man -- not a good leader.

Franklin Roosevelt, while not a particularly good man, was an exceptional leader. The general principle is that Cromwells guiltless of their country's blood are like mute, inglorious Miltons -- a contradiction in terms.

Similarly with individual excellence. Alexander Hamilton excelled in all he did. But he threatened others and sharpened differences. Washington, though not so clever or so diligent, cut a figure around which others could rally. He fostered fellowship and was a superior leader.

As to the command decision, it is the least reliable of guides. People with a poor feel for other persons try to force the consensus from on high. They make daring, risky decisions the better to assert themselves.

Natural leaders nurse consensus and bring others around. They do not bet on 100-to-1 shots. They move only when the odds are overwhelmingly in their favor. They are like Eisenhower on D-Day -- not Nixon going into Cambodia.

Because working with others is so important, there are times when even the mightiest figures cannot lead. At present in this country high hopes for collective action have withered in disappointment. Most of us seek comfort in better living and private actions. The scope for leadership seems small -- and those who deny that fact are charlatans, not leaders.

Still, even in these days, there remains a kind of American conscience -- an awareness of where we have been, where we are now and where we ought to go. The disposition to sacrifice is not dead, provided goals can be identified and the road to reach them laid out.

But the road cannot be identified belatedly by reaching to events and reading the polls. The trick is to develop by an internal reading of feelings and instinct an advance sense of where ordinary men are tending. That is not easy. That is different from fearing God and loving one's family. That involves becoming, in a time of confusion, the keeper of the nation's conscience. But that, after all, is what leadership is all about.

If this analysis is correct, it is easy to see why Jimmy Carter stands so low in the polls and is so much on the defensive. It is not a question of looking tall and sounding tough. Carter's problem, as witness his latest maneuvers with the Russians on Cuba and with labor on inflation, is that he lags behind the flow of events.