I collected them because I liked them. It isn't my fault that today this junk is worth millions," cracks George Costakis, 66, of his collection of avant-garde Russian art. As a native Soviet employee of the Canadian embassy in Moscow, he covered the walls of his seven-room apartment with Kandinskys (he owned 25), Chagalls (20) and Rodchenkos. More than 2,000 masterworks in all were stored in the Costakis home, which became a must stop on any Soviet tour for Western VIPs and art curators. David Rockefeller once turned the page of the guest book so he wouldn't have to sign right under Ted Kennedy, who had been through not long before. Sometimes 80 people visited in a single day.

Then in January 1978 Costakis—who had tried to emigrate four decades earlier—finally negotiated an arrangement with the Kremlin. He agreed to leave behind 80 percent of his art in exchange for exit visas for himself, wife Zina, two of his four children, a daughter-in-law and a grandchild. The Soviet government brooded a year deciding which works, of what was the world's largest and finest collection of the genre, would be retained by Moscow's Tretyakov Gallery. "They took the best," sighs Zina, who had more than emotion tied up in the collection—she sold her car, her diamond ring and her fur coat to help support her husband's art-collecting habit.

Next week 15 of the paintings Costakis surrendered to the Soviets will be unveiled in a keenly anticipated "Paris-Moscow" exhibit at France's Pompidou Center. The approximately 400 works he retained have been sent to New York's Guggenheim Museum for restoration and documentation. The family, having moved first to Rome and then to Athens, will eventually follow them to the U.S., where Costakis has already visited on lecture appearances. Travel aside, he has lived frugally for a man with individual paintings worth up to $500,000. "I know people are waiting to buy, but they will wait a long time," he declares, determined to keep his remaining collection together.

Costakis does not cite political reasons for his self-exile. "Life became difficult," he shrugs. "The apartment was no longer a home, but a museum. It wasn't safe to live in the flat with all those treasures." Two robberies and a mysterious fire helped convince him it was time to go but, he says, "Russia is like my mother. I don't want people saying bad things about her." Another reason for his reticence is that two brothers and two of his daughters and their husbands remained behind.

The son of a tobacco merchant who moved from Athens to Moscow in 1905, Costakis had always retained Greek citizenship. As an Orthodox altar boy "surrounded by beautiful things," he began collecting "little" items. Over the years he was able to acquire Dutch paintings, Russian silver and antique porcelain, which were affordable because only foreigners were interested. (After 1917 his father was reduced to being a guard at the Greek embassy, and later, for a while, George served as its chauffeur.) World War II broke out while Costakis was doing odd jobs around the diplomatic community. He would have emigrated in 1939 but had already married Zina, a Russian who could not leave. By the mid-'40s Costakis was bored with his childhood collection and started to exchange it for then-discredited works like those of Chagall, Kandinsky and Malevich. Later other avant-gardists, who painted drab, ponderous murals for official buildings by day and brightly hued abstract work by night, sought out Costakis. Since the painters' work could not be exhibited, Costakis bought it cheaply. The most he ever paid was $600 for Kandinsky's Red Oval in 1955—about one-seventh the price it would have commanded in the West. All the while, Costakis kept a salon for artists who sang to his guitar, ate Zina's good cooking and washed it down with vodka. For many underground artists, Costakis was the sole source of support.

In Athens Costakis has surrounded himself with paintings he did himself, many of Russian scenes. He has acquired no art and rents his house. "To have no money is very bad," he observes. "To have a lot of money is worse." Then Costakis adds convincingly: "I didn't collect art for money."