The opening passages of the 40th session of the General Assembly of the United Nations have served compellingly to remind us of how often history produces effects directly contrary to those the hopeful had expected from it. Very little has burbled from the podium so far to diminish the suspicion that four decades of the U.N.'s history have worked, not to widen the horizons of its member states, but to narrow them to their own borders.

Secretary of State George Shultz did essay a global perspective, but he hopped so capriciously about the universal murk of the international landscape to point to the shining white of one shade of gray and the pitch black of another that his auditors might be excused for wondering how anyone who views the world as this gapingly divided could aspire to negotiate any easement of its quarrels.

But this, of course, was not the real George Shultz, who is a shrewd and tolerant negotiator. This was instead the American secretary of state speaking in the U.N. mode, which is to say that he was talking not to the world but to his own domestic establishment, and especially to those civilians in the Pentagon who think him a softie.

The real audience for any spokesman for a member state in the General Assembly is the citizenry of his own nation, and nothing can more damage him than a conciliatory tone toward most other countries. The sitting president of the United States is the only public employee who can get away with this sort of thing.

Ronald Reagan is accustomed to addressing international forums in the fashion with which he used to open shopping centers, and we can look forward to his going to the United Nations this month to shower his blessings upon the just and the unjust alike.

But, for presidential subordinates, the appointed posture, as it was for Shultz, is stern resistance to the contagions of evil.

The only three national figures to go on from the United Nations to grander employments were Henry Cabot Lodge, Daniel Patrick Moynihan and Jeane Kirkpatrick. Lodge contrived his celebrity by quarreling with the Russians on the Security Council with a fierceness quite at variance with his genteel disposition. Moynihan and Kirkpatrick strummed the heartstrings of all good Americans by treating the emerging nations to variations of condescension and contumely. On the other hand, Jimmy Carter's ambassador, Andrew Young, confused his functions with diplomacy, and strayed into such unsafe paths of give- and-take that he could only be got rid of.

We ought not to be blamed for approaching the parliament of man as though it were no more than a megaphone for broadcasting the national will. It is that sort of parliament, and nearly every member uses it the way we do. Why, as an instance, is Poland's premier, Gen. Wojciech Jaruzelski, preparing to come among us?

Not, we may be sure, to appeal to the civilized portion of mankind, an office for which his qualifications are below average. He voyages with his kept journalists, and he trusts them to invent enough panoply for him to create a measure of delusion among the Poles back home that they are oppressed by a world statesman of distinction.

He will even extort a few ceremonious welcomes; our president doesn't have to see him, but his bankers do, because he commands respect as an international deadbeat. That is a curiously elevated status these days, and this week the president of Peru arose to announce his country's defiance of its creditors. However dank it may otherwise be, the General Assembly at least provides the unique refreshment of an atmosphere where bad debtors can freely bully bankers.