In a Georgetown garden, half hidden by a high wall, is a huge mosaic mural depicting in a kaleidoscope of color the artist's flight to America and the happiness he found here.

Marc Chagall, who died in March at 97, gave the mural to his friends Evelyn and John Nef in 1971. He designed the mosaic in his studio in St. Paul de Vence, France. Lino Melano, the Italian artist, executed the design and then shipped it off to America in 10 huge slabs that were later fitted into a custom-made brick wall.

The 10-by-17-foot mosaic contains themes of Greek mythology with the winged horse Pegasus, music with Orpheus and his lyre, and eternal love with two lovers secure beneath a leafy tree. The overriding theme is of an optimistic future. In one corner are groups of refugees striving toward the skyscrapers of New York City.

"As a Jew he was in a terrible position during the war until he emigrated to the United States," Nef says. "He felt that his life had been saved by the United States and he wanted to say 'thank you.' And so he does this in a big way in this mosaic that he did for us."

Escaping the Nazi invasion of France, Chagall and his wife Bella arrived in New York in June 1941.

That same year Nef, then a history professor, founded the University of Chicago's Committee on Social Thought. Guest lecturers were to include T.S. Eliot, Arnold Schoenberg, Igor Stravinsky and, in 1946, Chagall.

"He had never given a lecture in his life, he had never been west of the Hudson River and he had never been in an airplane and he never traveled anywhere without his wife -- his wife had died of pneumonia in 1944 ," Nef says.

Chagall at first was leery about lecturing. But he relaxed when he saw two pictures he had painted in Russia before the first World War hanging in the Nefs' house.

"And this so loosened his tongue we talked all evening, and I've never heard him talk better," says Nef, citing a friendship of 35 years' duration.

They were drawn to each other by similarities in their lives. Both were widowers at an early age. Both remarried.

"I've never had any systematic relations with him ever, we just talked," Nef says. "I still remember what he told me the first time we met: 'Everything I've done in my life has been determined by my art.' And it's true."

Nef recalls Chagall telling him how, as one of 10 children of an impoverished barrel maker in Russia, he was taken by his mother to have a local artist evaluate his work.

"He trembled when he went in, and the painter looked over his sketches and said, 'Well, he's not without talent.' This was rather noncommittal. But he breathed easier because he was afraid he'd be shut off."

Chagall went to France, where he met Picasso, Matisse and Rouault.

"He didn't believe he was any good in those days," Nef says, adding, "he became very discouraged."

He returned to Russia, and following the revolution served as commissar of art for a short time, Nef says. "He finally got scared to death."

With his wife and child, Chagall returned to France and lived in Paris without a passport, unable to travel. A group of friends concerned about the artist's safety asked President Vincent Auriol to give him an international pass.

"Auriol looked at them, and he said, 'Je pre'fe re que le maitre soit franc,ais,' I prefer that the master become French. And so he made him a French citizen," Nef says.

French status made it possible for the Chagalls to enter the United States, their country of asylum during World War II. Which led to Chicago. Which led to Georgetown, and the mural that commemorates it all.