After 15 years of negotiations with the Czechoslovak government, nearly 400 objects from a vast collection of Judaica assembled by the Nazis for a "Museum of the Extinct Race" has arrived in Washington for a major exhibition at the Smithsonian Institution.

"The Precious Legacy: Judaic Treasures From the Czechoslovak State Collections" is a sampling of 500 years of Jewish art and life gathered and shipped to Prague just as the Jews themselves were being sent to death camps. The experts who catalogued the collection--everything from pianos to cut-glass pitchers, from the prayer books of a village synagogue to sheaves of medieval manuscripts--were Jews who, upon completion of their task, were deported and killed. In 1950 the Czech government took over the collection and created the State Jewish Museum in Prague.

The loan exhibition will be shown for the first time outside Czechoslovakia when it opens Nov. 9 at the Evans Gallery at the Museum of Natural History, where it will be on view through Dec. 31. It will then travel to Miami Beach, New York, San Diego, Detroit and Hartford, Conn.

The process by which the exhibition came to the United States began in 1968, when Charles Vanik, a Roman Catholic congressman of Czech descent, visited Prague's medieval Jewish quarter, accompanied by his legislative aide Mark Talisman, and broached the idea of an exhibition in the United States. The Czechs agreed in principle, but implementation then had to be worked out with the many-layered state bureaucracy.

"Between 1968 and 1979, the project was laid on the shelf," said Vanik. "Mark Talisman, now the Washington representative of American Jewish communal institutions went through one agony after another. He'd deal with one person and then someone else intervened. The professional diplomats wanted the project, but had to work their way through the system. I can't answer who held it up." Vanik, who speaks Czech and has devoted much time to promoting better U.S-Czechoslovak relations, pressed his proposal during half-a-dozen visits to Prague during the 1970s.

"The Czechs are the most frozen Stalinists, three times worse than the Russians," said one foreign service officer, a frequent visitor to Eastern Europe, who asked for anonymity. "Normally, the Czech government wants to keep the lowest possible profile here. To send out the treasures of the Prague Jewish Museum means that the fate of the Jews and the Czech regime gets reviewed, which opens up too many questions."

Asked for his explanation for the delay, Talisman said, "Let's just say that Czechoslovakia is not your typical international cultural loan country."

Jaroslav Kubista, of the Czechoslovak Embassy here, had this explanation: "The idea was developing a long time. At the beginning, neither side had a perfect idea. Some political questions are involved."

In 1979, Vanik was told by the Czech foreign minister that the exhibit had been approved. He promptly telephoned Talisman, who was on vacation--the call had to be patched through from the American Embassy in Prague to a laundromat in Cape Cod. Forty-eight hours later, Talisman was on his way, accompanied by two American Judaica experts.

The storage rooms were unlocked and the Americans were shown the entire collection. For the first time, they were allowed to take photographs.

"Seeing the material was mind-boggling," said Linda Altshuler of the B'nai B'rith Klutznick Museum here, who went five times to Prague. "They have their exhibits and storage areas in as many as seven buildings. In one old synagogue are all the textiles, another old synagogue has all the silver. Attics, basements are full, and the items are clean and meticulously catalogued. There are case after case of similar objects.

"One gets the feeling of confiscated property--it is all so wholesale. You walk up three flights of stairs and open a locked door, and there are, from the floor to the ceiling, cases of Torah finials. Or charity boxes. Or Torah ark curtains. You start thinking how many people the objects represent. I work in a small museum where we consider ourselves fortunate to have several dozen Torah finials. In Prague they have hundreds, even thousands."

Experts estimate the Holocaust destroyed 90 percent of European Jewry's liturgical objects. Yet the Prague museum has rooms crammed with hundreds of Torah mantles, many of them executed with stunning craftsmanship, and Sabbath wine cups, circumcision knives, seven-branched candelabras and other necessaries of Jewish religious life. There are also the finest quality 19th-century oil paintings of luxuriantly bearded rabbis and dignified merchants, and children's drawings of trees and butterflies from the Nazi concentration camp of Theresienstadt.

After World War II, ownership of the collection reverted to the Jewish community--those few thousand Czech Jews who returned from the camps--which set up a museum in 1946 in synagogues of the medieval Jewish quarter. Following the Communist takeover in 1948, the state took title to the museum; in exchange, it paid the curators and maintained the collection.

In a 1968 book, Vilem Benda, then director of the museum, describes how this transfer took place: "The Council of Jewish communities, as the highest organ of the surviving Jewish community, occupied with worries to provide materially for its members, discovered before long that it was beyond their powers to finance the establishment of the museum. At its session in November 1949 they discussed a proposal to offer the museum premises and the entire collections to the Czechoslovak state as a gift. The Government of the Czechoslovak Republic discussed the proposal at its meeting on April 4th, 1950 and generously decided to accept the gift . . . The museum ceased to exist in isolation and became an equal partner of all Czechoslovak museums helping to educate the new generations in the spirit of socialism."

Thus the relics of centuries of Jewish piety collected by the Nazis came under the guardianship of a staunchly atheistic communist government. It was a transaction worthy of Franz Kafka, who was himself a Prague Jew.

There may be as many as 15,000 Jews left in Prague, but only 2,000 attend synagogues. The Jewish Museum, however, is one of the city's great tourist attractions, with 800,000 visitors a year--the great majority not Jewish and the largest single group among them Germans.

"I was overwhelmed by the beauty and the wisdom of the people who created and used the items," Talisman said. "This is not a collection in which the viewer is expected to descend into a grave. The drawings of children in the concentration camp of Theresienstadt is the greatest collection of optimistic art." (These drawings will be shown in a companion exhibition at B'nai B'rith's Klutznick Museum.)

For Talisman, it was one thing to learn from history books that there had been 400,000 Czech Jews before World War II. But the finality of their death was expressed for him when he saw cases full of Havdalah candles with blackened wicks--burned briefly at the end of the Sabbath--that would never be used again.

Talisman was shown a drawer full of knives ritual slaughterers used. He tested one, a huge knife from the 18th century, and nicked his thumb. "What a klutz I am," he remembers thinking. "But what an incredible privilege it is to hold such a knife in your hand!"

Talisman and Anna Cohn, the Smithsonian's project director for the exhibit, have lost count of the number of times they visited Prague.

"The Czech curators were wonderful," said Talisman. "But the government officials were skittish: This is their national treasure, lovingly maintained, and they have the right to decide about it."

"Throughout the negotiations, the preeminent Czechoslovak concern was security, but as to the security of what, we never got an answer," said Ron Neitzke, who was the State Department's director of Czechoslovak affairs in the 1980s, until the final stages of the negotiations this summer.

"Since the items were heavily insured, there was never any question of monetary loss," said Neitzke. "We had to develop a secure feeling in the Czech government that the items would be returned."

Neitzke believes that the main stumbling block was the 18.4 metric tons of Czechoslovak gold reserves, entrusted to the Western allies by the democratic Czech government during World War II and finally returned to Prague in February 1982. Negotiations over the gold went on for years, and at one point, in 1974, the U.S. government pulled back at the last minute.

"We had a heritage of perceived bad faith on both sides," Neitzke said, "and no major accomplishments. There were moments when we had doubts if the exhibit will ever come off. That we got it through was nearly a miracle."

In 1982, the American Embassy cabled Talisman that the Czechs were ready.

"I was buoyant," Talisman says. But just before he was due to leave for Prague, he developed chest pains and failed a stress test. His doctor strongly advised him not to go.

Talisman flew to Prague. A special U.S. Air Force medical plane was kept in readiness in Frankfurt in case he had to be sent home.

But Talisman was lucky. "My heart held out," he recalls, "and the Czechs agreed to a two-year exhibit traveling through the United States, to a joint selection process and to an opening at the Smithsonian in the fall of 1983. Within 20 minutes they granted everything I asked for. I couldn't believe it."

Philip Morris Inc. agreed to become the corporate sponsor with a contribution of $350,000. The cost of presenting the exhibit is more than $1 million; most of it is being paid by private donors.

Talisman said he could accept the reality of the exhibit only after the items arrived in the West.

Cohn said she always had faith that the exhibit would happen--"a rational faith," she said, based on "the tremendous good will" among Czechoslovak curators and cultural affairs specialists. She said she felt "reassured" by "the old world craftsmanship" of the movers, employes of the German firm Hassenkamp, which also packed the King Tut exhibit that came to the United States in 1976. They cut special, acid-free foam rubber padding for each item, then came layers of bubble paper and foam packing--all to be placed in a cardboard box protected by a padded wooden crate. She felt "heartened" by the cooperation of the Czech customs officers and cultural ministry officials who checked each item as it was packed.

"In the end it was like clockwork," Cohn said. "It took the moving company five days to pack the exhibit. All was done by Friday 5 p.m. Before sunset. I checked and saw that everything was packed. Then I took a broom and swept the synagogue where the crates were kept. The workmen tried to take the broom from me.

"They didn't know that it is one of the highest honors in Jewish life to clean a synagogue."