With his recent appearances and statements on nuclear arms limitation, Soviet President Leonid Brezhnev has returned to the public scene after his recent illness. But for the Soviet public, which gets its news almost exclusively from the media here, Brezhnev never left.

The 75-year-old Soviet leader's four-week public disappearance was a major international news story. But the Soviet media has not said one word about it nor has there been any official explanation.

Given Moscow's obsession with secrecy, this is hardly unusual. To be informed here is a privilege, not a right. The traditional attitude is that information should be given on a need-to-know basis. In this case, the Kremlin clearly decided that the 260 million Soviet citizens did not need to know about their leader's ailment.

This posed a knotty problem for foreign correspondents here. Russians seem to think it odd and suspicious that anyone should concern himself with the details of subjects that are not in his field. It seems almost improper, for instance, to ask a spokesman of the Soviet airline Aeroflot how many aircraft it has ("Many" was the reply).

When it comes to matters of state policy and leadership changes, there is hardly anyone to turn to for information. Both the Tass news agency and the daily Pravda, official organs of the country and the Communist Party, maintain a prolific silence on such issues.

As far as the Soviet media are concerned, Kremlin leaders never get ill, nor do they argue with one another over policies, nor do they make mistakes while in power. The information vacuum surrounding the crenelated walls of the Kremlin is designed to project an image of harmony, tranquility and stability.

It is not a perfect vacuum. The absence of information generates rumors among the elite. Some information trickles out in dribs and drabs, either from Soviet officials on the Kremlin's fringes or from East European visitors. Yet for foreign journalists here, the information is almost impossible to verify with anyone in a position of authority.

The extraordinary thing about rumors surrounding Brezhnev's recent illness was that they were so widespread they reached the level of barbershops, schools and factories. The resulting tension and the absence of information led to speculation among foreign observers. Who was spreading the rumors? Who stood to gain from them?

Ever since the death last January of Mikhail Suslov, the number two man in the Kremlin hierarchy, there have been indications of a power struggle among top figures jockeying for position in what is generally perceived as the twilight of the Brezhnev era.

This jockeying was not directed against Brezhnev, although the ultimate prize is his post once he leaves the political stage. There was speculation among foreign analysts here that much of the infighting was directed against Konstantin Chernenko, a Brezhnev protege, who was taken into the ruling Politburo less than four years ago and whose sudden rise is believed to have been opposed by other senior figures.

According to this argument, Chernenko has tried to consolidate his authority while his patron was still in charge. Various rumors, including those linking members of Brezhnev's family to certain corrupt practices, were seen as part of an effort to prevent Brezhnev loyalists in the Politburo from installing Chernenko in Suslov's old post.

On a broader front, the rumor mill also appeared to reflect a conflict between those favoring cautious, incremental shifts in policies and younger party leaders seeking more fundamental changes.

All this was speculation. Yet even though Brezhnev's reappearance restored normalcy to political life, the issues raised during the unsettling days of his disappearance continue to percolate within the elite.

The only apparently reliable information about the Soviet president's condition came from well-informed officials who privately said Brezhnev's health had indeed deteriorated seriously during a visit to Tashkent, and that he may have suffered a mild stroke aboard the plane returning him to Moscow March 25. Although he was hospitalized, they insisted that he was not incapacitated--a fact confirmed when a clearly ailing Brezhnev appeared in public four weeks later.

As rumors spun off from this one bit of information, the number of Soviet sources available to Western diplomats and journalists shrunk almost overnight. The Foreign Ministry, in the only official government response, said Brezhnev was on vacation and denied a Newsweek account that he was ill.

Then, in the fourth week of Brezhnev's convalescence, rumors circulated that he was near death or had already died.

In the absence of authoritative sources, foreign diplomats and journalists began driving around the Kremlin and the Central Committee building. Since only Politburo members and Central Committee secretaries are entitled to the luxurious Zil limousine, the sight of long black sedans parked there would indicate an important meeting.

The confusion was made even greater because staffers of Tass, Moscow television and official journals were also talking about the death rumor and searching for clues themselves. A Soviet journalist reported that Brezhnev's name was deleted from a nonpolitical magazine article scheduled for publication in July.

Nobody seemed able to pinpoint the source of the death rumors. While Western broadcasts beamed to the Soviet Union may have helped spread the word of the leader's illness, there is a general agreement that the rumors of his death originated here.

None of this was reflected in the Soviet media, which continued its steady diet of uplifting stories about coal miners who overfulfilled the production plan and exhortations to farm workers to do their utmost during spring sowing.

Later, after Brezhnev's public appearance ended rumors of his death, Soviet officials privately sought to convey the impression that the public had been spared the agony of being informed about their beloved leader's illness, and that Western journalists may have been malicious in their efforts to find out details of Brezhnev's ailment. Also, they noted, it is the traditional Russian way of protecting the leader's privacy.

As for possible personnel changes, one is told that few are likely in the immediate future. Even if there are some, the officials said, Moscow's domestic and foreign policies are not going to change because they are based on a broad consensus within the entire leadership.