One can suppose that the news from Moscow this week will go into Russian history books. It was the week when the mighty Kremlin rulers publicly yielded for the first time to an individual.

The issue at stake was hardly momentous. On Nov. 22 Andrei Sakharov, the country's foremost dissident, began an indefinite hunger strike in a desperate effort to obtain an exit visa for the wife by proxy of his stepson, who lives in the United States. Seventeen days later the government conceded. Sakharov and his wife, saying they were "happy beyond words," started taking food again.

No government, least of all an authoritarian one, can easily take such a decision under the glaring light of worldwide publicity.

The question is why did the Kremlin act in this way and what does it tell us about internal conditions in the Soviet Union?

In a broad sense, the Sakharov case illuminates several contradictory aspects of life here. It shows how much things have changed since the days of Stalin, when dissent was impossible.

Yet the fact that in the 1980s the authorities are using the ancient method of internal exile to silence dissent -- Sakharov had been banished to Gorki, a city 250 miles east of here, two years ago -- seems to illustrate to what extent conditions remain the same.

In this context, the 60-year-old physicist follows a string of major figures of the reformist intelligentsia and leaders of the dissident movement.

Like Leo Tolstoy, who after completing "Anna Karenina" in 1876, gave up a brilliant career as a novelist to preach his own form of Christian ethics to the masses, Sakharov gave up an equally brilliant career as a physicist to struggle for human rights in his country.

It is his passionate sincerity and the attachment to the reformist tradition of moral dedication and utopian hopes that generate respect for Sakharov even among his fiercest opponents here.

Soviet authorities have used the same method. But even in the isolation of Gorki and with only a handful of real followers here, Sakharov remains a problem because the spell cast by his quest for a moral world finds resonance among many members of the elite, particularly scientists and technocrats.

So far, it has been regarded as inconceivable that the authorities would deal with the problem by simply sending Sakharov and his wife to the West. He is one of the leading theoretical physicists in the country and was involved in the Soviet military industry until 1968 when he criticized government policies in an essay.

During the past few years, Sakharov's pronouncements suggest that he had become increasingly frustrated by growing isolation, on the one hand and by repressive measures against his dissident friends on the other. He has commented on virtually all major international issues from Cambodia to arms control, mostly bitterly attacking Soviet positions.

The extraordinary situation in all of this is that other Soviet citizens would have been sentenced to jail terms on treason charges had they made similar charges.

According to those who know him, Sakharov's frustrations centered on the fate of Liza Alexeyeva, 26, a woman his stepson wanted to marry. Sakharov had pledged he would do everything possible to obtain an exit visa for her, yet he was repeatedly frustrated in his efforts.

The case itself was weak, from a Soviet legal point of view. The stepson, Alexei Semenov, a graduate student at Brandeis, had been married before, and his wife and child had been given permission to leave for the United States. They subsequently divorced in the United States. Semenov last summer married Alexeyeva in a proxy ceremony in Montana, a procedure that has no legal standing under Soviet law.

In an article in the government newspaper Izvestia, the authorities provided details about the case and quoted extensively from Sakharov's interviews with Western newspapers to demonstrate his lack of patriotism.

Judging by remarks in recent days of various Soviet citizens including Sakharov's sympathizers, his standing has been damaged somewhat.

That the government subsequently yielded to his demands was without precedent. It will probably enhance Sakharov's standing in the West because he was risking his life to act on his liberal values.

The Associated Press reported that Alexeyeva had visited Sakharov and his wife, Yelena Bonner, in a Gorki hospital. She told reporters Sunday that they appeared weak after their 17-day hunger strike but have eagerly started on the road to recovery.

If this is seen as a victory for the cause of human rights, it is a modest one. Other intellectuals here will not benefit from it. Indeed, the drastic protest over a relatively minor issue may weaken the effectiveness of more moderate reformers.

It is not known what the authorities calculated when they decided to relent. Among the most important factors were pressures from within the scientific elite as well as foreign policy considerations. Moscow clearly wanted to show flexibility at a time when it is seeking to influence public opinion in Western Europe.