"A lot of people have such a pejorative feeling about icons," says Gary Vikan, associate for Byzantine Art Studies at Dumbarton Oaks. "They see 17th-century Russian icons, that are so stylized, so limited."

But he thinks they'll change their minds when they see the newly acquired, late 13th- century wood panel portrait of Saint Peter, painted by an unknown artist of Macedonia. The icon, on display at Dumbarton Oaks with 12 others, is considered the most significant acquisition of the Byzantine Collection in about 20 years.

Besides showing icons of rare quality, the exhibit demonstrates the use of the religious painting in Greek Orthodox worship. And this group of panels, from 1200 to 1400 A.D., seems to anticipate early Renaissance art. By the time these were painted, the preoccupation of monks had turned from illuminating manuscripts toward painting icons.

Few panels have survived the vicissitudes of history.

What makes these panels so special is that they're among the few Byzantine icon paintings outside the Monastery of St. Catherine. At that monastery at the foot of Mount Sinai, Vikan estimates, three-fourths of the world's icon panels are preserved -- and likely to remain.

Kurt Weitzmann, a leading authority on Byzantine icon painting, doesn't think any icons have left Mount Sinai: "The monks are very cagey and conscious of their treasures." And, he says, "they don't need money."

The tradition of icon painting existed at the monastery from the sixth century to the late 1950s, when the last painter/monk died. Weitzmann, a professor emeritus at Princeton University, was at Mount Sinai when the funeral was held. As part of a burial rite, a 14th-century icon of Christ was placed on the monk's chest but not buried with him. The monk's remains stayed in the grave for three years, says Weitzmann, and then his bones were taken up and buried in a common grave with the bones of other monks -- another tradition.

His name was Pachomios, and he did much to help preserve the more than 2,000 icon paintings owned by the monastery.

By the time of his death, icon-painting had broken down as a branch of art, because it had become so modern, says Weitzmann. "But," he says, "it still was a holy act for a monk." MASTERPIECES OF BYZANTINE ICON PAINTING -- At Dumbarton Oaks, 1703-32nd Street NW, through June 26. Open daily from 2 to 5, except Mondays.