MUSEUMS FOR too long have chilled the art of Africa. The objects they display -- masks no longer worn, staffs no longer danced, gods no longer worshipped -- look M sterilized by coldness. They glow as if frozen in their plastic cases. Most museum exhibitions of Africa's old art, even the most beautiful, are more dead than alive."Four Moments of the Sun: Kongo Art in Two Worlds," which goes on view today in the East Building of the National Gallery of Art, is, at least in spirit, a remarkable exception. It struggles to cast light on the blues of Robert Johnson, the dances and the pottery of South Carolina, Mississippi magic and the shows of the Supremes. Its grave markers and cloth mummies were once made for the dead, yet before one leaves this show they seem to pulse with life. The two worlds are not only the connected realms of the living and the dead, but those of Central Africa and of black America -- in whose music, language, dances, gestures and cosmologies, much that comes from Kongo has, almost miraculously, managed to survive.Such trans-oceanic links between the Old World and the New have been glimpsed before. One feels them in black churches, hears them in black music, sees them in black "flash." The viewer who examines old masks from black Africa cannot help but feel a ghost of recognition when he notices, with fresh eyes, the headgear, hats and hair-dos he encounters in the street. Forced removal, slavery, the loss of old beliefs, of tribal bonds and language, have thinned, but have not severed, all the ties that bond New World black populations to their Old World roots. The Kongo exhibition makes such ties explicit.

It was organized, with passion, by Prof. Robert Farris Thompson of Yale University and Fre re Joseph Cornet, director of the Institute of National Museums of Zai re. The catalogue they've written makes long-mute objects speak.

The kingdom of Kongo, in its heyday, governed many hundreds of miles of Central Africa's west coast in what is now Angola and southern Zai re. Kongo gave to Africa extraordinary art. One-third of black Americans are of Kongo ancestry.

Of the 90 objects on display -- terracotta grave markers, wooden drums and carvings, small statues of soft stone, and cloth-covered mummies -- some two-thirds show the viewer one coded, complex emblem. It sometimes is a cross with small circles at each ending; it sometimes is a spiral, a square or quartered circle. To the people of Kongo, it is a cosmogram as meaningful as the cross is to the Christians. Like the cross, it signifies the sacred, the order of the cosmos, and the path to life eternal. No matter what its image, its meaning is the same, hence the title of the show: "The Four Moments of the Sun."

Those four moments mark the cycle of the moving, ruling sun. They are dawn, when day and life begins; noon, when both are at their peak; sunset, which brings fading; and midnight, when the sun shines on the kingdom of the dead. The funerary objects here did not, in Kongo terms, mark a final resting place. Instead, they viewed the cemetery as a threshold or a door, as the place of mediation between the two connected worlds of the living and the dead.

The catalogue accompanying the Kongo exhibition is far more than a picture book. It does much more than describe. Thompson, in his essays, offers us a scholarly, if occasionally far-reaching, guide to Kongo civilization, morality, theology and law. Following his teachings we begin to comprehend the messages and meanings of the gestures and the symbols of the pieces on display.

Look, for instance at the "Grand Oath-Taking Image," borrowed from the Detroit Institute of Art, which is the single most impressive artifact on view. It "stands with hands on hips, a position (pakalala) which symbolizes brave readiness to take on any lawsuit, no matter how severe." It bristles with a hundred nails, screws and knife-blades that have been driven with great force into its old wood. Thompson tells us why they're there. Each blade seals a covenant or marks the resolution of some legal conflict. The insertion of a blade or the pounding of a nail, its metal sometimes licked by both parties to the lawsuit, brings the matter to an end. The awesome image here, studded with its precedents, no longer appears alien. Instead, its nails call to mind the gavels used by judges and by auctioneers.

Many of these objects communicate by gestures. The reliquary manequins hold their right hands upwards, indicating heaven, while their left hands point to the horizon, gestures showing that they mediate between the living and the dead. One terracotta marker here shows a figure, head upraised, hands held aloft with fingers spread, in a sign of praise and blessing. That joyous gesture, Thompson notes, is repeated daily in Afro-American churches by celebrants in song.

He believes that other gestures, apparent in these artifacts, live among us still. The Tuluwa lwa luumbu gesture of self-encirclement, with arms crossed on the chest, is still being used to end conversations, or so Thompson claims, in Kongo and New Haven. The pakalala gesture of the "Grand Oath-Taking Image" survives in the United States, writes Thompson, as "the classic black woman's challenge pose." The Supremes, he notes, sang "Stop! In the Name of Love" while "striking the very pose Kongo elders used to stop misbehavior: left hand on hip, right hand or palm before the body."

Thompson also notes that Robert Johnson's blues of 1936 -- "I went down to the crossroads, fell down on my knees" -- suggests the living power of the central Kongo cosmogram. He cites other bonds between the Old World and the New -- conga drums, for instance, "(the name betrays their history)," and the pierced shells emplaced still (the cosmogram again) on black graves in the south, and South Carolina's skull-shaped Toby jugs, which Thompson believes recall the days when Kongo chiefs drank from human skulls. Thompson thinks that "bottle trees" found in the deep South are also based on Kongo lore, and that the red cloth used for Kongo reliquary manequins may have lent its hue to the Afro-American folk charm called "High John the Conqeroo."

Language is another link that Thompson here explores. The word "boogie," he contends is a tracing from mbugi, the Kongo word for devil. "Peanut" in Kongo is nguba, hence "goober;" and tuta means "to carry," which may lead to "tote."

Thompson's arguments, at times, may appear a bit far-fetched, but he is a gifted writer and a serious scholar (his two essays in the catalogue carry 550 footnotes). His last effort for the National Gallery was "African Art in Motion." Thompson surely cares. Few scholars in America have done more than he to make the art of Africa comprehensible, alive.

The show has been installed in the lobby of the gallery's Center for Advanced Study in the Visual Arts, where it sets up a strange counterpoint with the gallery's exhibit of the sculptures of Rodin. "The Four Moments of the Sun" may appear to be, at first glimpse, yet another grouping of powerful, impenetrable, ethnographic artifacts. But he who reads the catalogue (or the wall labels will do) and compares what he has learned with the works of art before him will leave with his thoughts swirling.

"This exhibition," writes Zai re's President Mobutu in his preface to the catalogue, "offers, for those whose forebears were originally from Bas-Zai re, an opportunity to re-establish contact with their ancestors." It may well do just that. It closes Jan. 17.