A lost painting, an insurance agent, and art history

The world has just gained a missing 17th-century French painting and lost an insurance agent to the intrigues of art history.

It all began in the fall of 1980 when Michael Brunner, working as an insurance agent to support his family, spotted a ''large, dirty'' painting in an Santa Ana, Calif., antique shop. It looked familiar to Mr. Brunner, who had majored in art history and had specialized in ''Caravaggesque'' art - paintings done after the style of baroque 17th-century painter Caravaggio.

Though he had taken a leave of absence from a master's degree program at the University of California at Santa Barbara (UCSB), scholarly habits die hard. After looking at the painting for about 10 minutes, Brunner decided to investigate its authenticity. Guessing that the painting was done in Rome between 1615 and 1630, he almost immediately pulled down a catalog with a photograph of the very painting he had seen -- ''David with the Head of Goliath'' by Valentin de Boulogne. A companion work, painted to hang alongside it, is in the Cleveland Museum of Art, but Brunner's find was listed as ''missing.

It was known that Cardinal Francesco Barberini paid for the painting in June 1627, and it stayed in the family (which was to the baroque period what the Medici family was to the Renaissance) until 1935. In the '30s, says Dr. Alfred Moir of UCSB, an authority on Caravaggio and Brunner's professor, ''dealers mined the Barberini storerooms,'' and the painting disappeared.

It almost disappeared again; when Brunner went back to Santa Ana dealer, he found it had been sold. But the intrepid insurance agent managed to find out the address of the buyer.

When he had looked up the sizes of the painting and its companion, he visited the buyer and measured it. What clinched its authenticity for Brunner was the fact that a strip of canvas had been added at the top and bottom of the painting to enlarge it at one time, and the strips were the size described in the catalog and Barberini archives. He managed to buy the painting for $4,000 - twice what the buyer had paid, but probably a fraction of the painting's worth.

Brunner then pieced together how ''David with the Head of Goliath'' got from 17th-century Rome to 20th-century Orange County, Calif. No one knows who bought it in 1935, but it turned up in the Yugoslavian embassy in Madrid in 1938. The ambassador took it with him when he emigrated to the United States in 1939. After his death, a nephew bought it and presented it to a family friend, the Rev. Vladimir Mrvchin of Saint Stephen's Serbian Church in Monterrey Park. The painting hung in his house until 1980, when he moved to a smaller house and gave it to the antique dealer on consignment.

Pierre Rosenberg, painting curator of the Louvre, has asked Brunner to lend the ''David'' to the Louvre for a show of French paintings in American collections. So, on Jan. 30, the painting joins other French works back from overseas. Half are masterpieces, the other half are, like Brunner's, ''unpublished,'' according to Mr. Rosenberg. The show will go to New York's Metropolitan Museum of Art in May and from there to the Art Institute of Chicago.

Brunner plans to sell the ''David.'' He will get a lot more for it than he paid; ''more than he makes in a year, and maybe more than I make in a year,'' Dr. Moir remarks.

But more important than the money, Brunner says, is the fact that he has gotten back his enthusiasm for art history. He had finished his course work for his MA but says he took a leave because it didn't make sense to him as a career.

''Art history loses its relevance, because as a student, you don't have a chance to get your hands dirty,'' he says. Now he is starting his thesis, a study of Caravaggesque painting for which Valentin's ''David'' is a perfect example.

He already is getting good marks from his advisor, Dr. Moir. ''His intelligence and sharp eye are starting him on a fine career,'' he says. Brunner says he would like to be an art dealer.

Pierre Rosenberg is delighted ''David'' has shown up. ''It proves the profession of art historian is an important profession,'' he says. ''In our modest way, we are helping the painters of the past to stay with us.''