People like to say Pacific Island art looks like late Picasso, but they can't have seen much of it, because as a body it has a passion and purpose that dwarf the work of any painter of picture.

Tomorrow the National Gallery of Art will open the most sweeping show ever devoted to the arts of Oceania from Hawaii to New Guinea. It is the first such exhibit since 1947 and contains much newly discovered work.

The show, in the East Building's lower gallery where the Dresden extravaganza was displayed, will last through Oct. 14.

Faced with 400 objects ranging from ivory beads to a 22-foot wooden crocodile, designer Gaillard Ravenel has outdone himself, building display cases out from the walls for side viewing, dramatically spotlighting the masks and figures, leading the viewers with a blessed minimum of explanatory graffiti from east to west, from Polynesia through Micronesia and Melanesia to New Guinea.

Dozens of different subcultures are represented here, in as many different styles, different media and different eras. Yet all the works leave on with a single overwhelming impression: awe. These carved figures, rooms and rooms of them staring terribly down at one, have an aura of magic. They were imbued with mana, the mysterious ritual power so much a part of Polynesian life, and because of this were sacred.

There are ferocious water gods from New Caledonia, dressed in shaggy capes symbolizing rain and set high on pedestals to scowl at us, implacable as the sea. There is a hollow-eyed mask made from a stump that seems to contain even now some vestige of its tree spirit.

There is, near the end, a broad skull rack from Papua presided over by a frighteningly real human head, built up from an actual skull, with authentic hair and dim-brooding eyes. The open-mouthed head, loaned by a museum in Stuttgart, looks lost and far from home, violated by whatever explorer took it from its natural place.

Traditionally, the island peoples passed off a cheerful, happy-go-lucky image of themselves for the benefit of the Europeans who "discovered" them: the laughing, rollicking Noble Savage of Rousseau, the Mr. Natural of the 18th century, benign and wise and sexually unfettered.

But in fact, as this absorbing show proves, life on the Pacific islands was bound up by rituals, attended by fear in a hundred forms. We get a sense of unseen menace in the gods and sprites who peopled the emptiness and must never be flouted, but placated with dances and shaman magic and idols. The people surrounded themselves with a bewildering array of images, amulets and charms.

Thus, nearly all the object here have ritual meaning: the figures decorating boat prows, the dolls elaborately carved for funerals, the curious two-headed creatures, the bird-men of Easter Island. To copy them or use them wrongly would destroy their mana, and this belief worked as a sort of copyright system, which may account for the amazing variety of styles found even among tribes on the same island.

For instance, an Easter Island mystery at least as fascinating as the giant stone heads on the beach is the hands and fingers on smaller carvings. They are presented with an accuracy and detail that is unique in oceanic art. One lifesize arm sculpted in wood is as realistic as a life mold. Other figures show a knowledge of anatomy far beyond that of neighboring islands. Why?

Next to this exhibit stands a huge mourning dress from the Cook Islands, an imposing structure of pearl shell, turtle shell, feathers and bark cloth. And beyond that is a roomful of decorative lintels, cunningly carved into filigree.

"You can tell when the Europeans came, by the carvings," said Douglas Newton, head of the primitive arts department of the Metropolitan Museum in New York.

"When these people got steel blades to work with (instead of sharp stones or animal teeth) they had practically a renaissance of woodcarving."

Carving techniques ranged from mere incisions, crisscrossing a surface in delicate patterns, to great whittledout votive dolls and masks from New Britain three and four feet high, as thickly entwined with carved branches and vines as the forest the people lived in.

One universal theme is eyes: Big round staring eyes that glare straight at you, impassive, vaguely accusing, godlike. Some are just pieces of pearl shell with an ebony nailhead in the center for a pupil. Some are hollows. Some so dominate the head that there is no head at all, only two unblinking circles.

"We're not entirely sure what they signify," Newton said. "They're obviously important. Every part of these things has meaning. Even the stilts over there: They're not for playing games. They were used in a ceremony.

Sometimes the meaning isn't symbolic but practical. He pointed out a funerary figure with what looked like rabbit ears on top. Not at all, he said. Those were braces to keep the dead person's head erect when he was propped up next to the carving.

Not much of the work here is conventionally pretty. It was made with a more serious purpose, and the words that come to mind are powerful, stark, majestic, frightening, bold, fierce.

But there are exceptions. The best of these you see as you come into the show: three brilliant red-and-yellow feather capes from Hawaii, dazzling enough to make your mouth curl up. Above them stands a dragon-headed Hawaiian temple god, superbly carved, guarding the treasures within. He looks a little worried, and he should: There's a lot to guard. CAPTION: Picture 1, Carvings of gods from New Guinea; Picture 2, detail of wood statue; by Ken Feil The Washington Post