The death in Czechoslovakia yesterday of an elderly philosophy professor reflects, in the most dramatic way, the stakes involved in the public quest for greater human rights by a relative handful of activists in Eastern Europe.

The professor was 69-year-old Jan Patocka, a gray-haired, pleasant-faced man who was one of the leading spokesman for the more than 400 signers of Charter 77, a citizen's manifesto demanding rights guaranteed under various documents that the Czechoslovak government had signed.

During an interview in Prague in January, another well-known Czech campaigner for civil rights, playwright Pavel Kohout, seemed to have a sense of foreboding. He said that those who were young and healthy could probably withstand the harrassment and psychological warfare being directed by the government at those who signed the charter.

But it could well take its toll, Kohout warned, among the older campaigners.

According to the reports from Prague, Patocka died of a brain hemorrhage. Several days earlier he had been interrogated by Czechoslovak security officials at Ruzyne Prison for 11 hours after he had unexpectedly met his own request with the foreign minister of the Netherlands.

Patocka's act was the first attempt by activists in Czechoslocakia to make a plea in person to a statesman from the West.

The move greatly embarassed the Czechs, who canceled the planned meeting between Dutch Foreign Minister Max van der Stoel and Czech Communist Party chief Gustav Husak. Patocka became the target of intense personal criticism in the government-controlled press and television.

He had been interrogated by the police several times since the charter was first written and slipped to the West for publication early in January. But less then two weeks after the latest session, and after the blitz by the media, he was dead.

Of all the dissident movements that have surfaced throughout Eastern Europe in recent months, the one emanating from Prague has taken on a special significance in both East and West.

Although the Czechoslovak dissenters do not seem nearly as numerous as the Soviets, Poles or East Germans, the eloquence and structure of legality on which Charter 77 is based has made it the single most respected document on human rights to come out of the East.

In an interview in Belgrade last week, Yugoslav autho-critic Milovan Djilas called the charter "the best text ever done in the East. It is not ideological, not just asking for communism with a human face. The charter is very solidly founded under laws, even the Czech constitution," as well as the United Nation's Resolution on Human Rights and the Helsinki agreements of 1975, which Czechoslovakia signed.

"That is the character of the dissent movement in Eastern Europe today," Djilas went on. "Even in Russia, the dissidents are trying to find the jurisdical basis for their activity, to go through the courts" and not so much through emotions.

As a leading spokesman for the charter, Patocka would welcome any reporter who could find his way to the professor's small house on the outskirts of Prague.

He spoke Czech, German, French and a little English. His book-lined study had heavy curtains across the small, ground-level windows, giving one of the feeling of sitting in a room and listening for code-words over the BBC during World War II. A big radio set in the middle of the room added to the feeling.

In the days before his telephone was removed, he would sometimes grant a telephone interview to a caller from Western Europe in the midst of another interview with somone sitting next to him.

Patock was not a Communist, though many of the activists are former party members.

When he was asked in January about the origins of the charter, he referred to the 35-nation Helsinki agreements of 1975 and their provisions on human rights.

"We felt this was a unique opportunity to present a certain civic attitude and to give back to the people a certain moral dignity. That dignity is still here," the professor said, "and it is already being observed in the way people have reacted to the campaign of pressure put upon them."