As the aging Georges Braque increasingly withdrew from society, he spent his time contemplating his work space. The studio became an obsession. In this limited subject he found expanded possibilities, capturing the African masks, paintings and sculpture, and metamorphosing palettes in hallucinatory jazz states. The resulting series of eight paintings took seven years -- after a head injury in World War I, he paced himself slowly -- and are among his most important works.

Three of the studios are included in "Georges Braque: The Late Paintings (1940- 1963)," marking the centenary of his birth and opening this weekend at the Phillips Collection. The 48 paintings in the show, many from private European collections and unfamiliar to Americans, show the co- creator of cubism reaching for new angles in his last 23 years. They demand more than one visit.

In three rooms, three billiard tables play geometric games, banking off their huge canvases at odd angles. Red paint puts English on the balls; felt ricochets toward the ceiling amid the cubist cue action. In the 1949 "Billiard Table," bird-like shapes in the background head for the viewer. Along with the studios, the billiard paintings are the Frenchman's largest, most striking works.

Some of the paintings are Picasso-like, in a vocabulary approaching clich,e. All are complex, nearly overpowering the museum's intimate rooms. All the world's a still life, from flying birds and pouring rain to energetic tablecloths. Objects are seen in relation to one another, always in flux. "For me no object can be tied down to any one kind of reality," Braque told an interviewer in 1957. "This file in my hand can be metamorphosed into a shoe-horn or a spoon, according to the way in which I use it. . . This metamorphic confusion is fundamental to the poetry."

Cubism was a noisy style, but during the war Braque's emotion quieted, his colors toned down. In "The Blue Washstand" (1942), the sky is stormy, the lines of the table are sad. (He documented the days when, lacking enough fuel to heat the whole house, the French took baths in the living room.)

Braque's recurring birds, more or less abstract but always facing right to left, have been called symbols of creation, life, soul or freedom. But Professor Herschel B. Chipp, who wrote the catalogue for the exhibition, says there's no evidence to support such allegory. "He liked the shape. He lived on the seashore most of his life and saw lots of seabirds."

In Braque's last painting, "The Weeding Machine," completed shortly before his death at 81 in 1963, the birds are barely suggested. In deliberate, vital strokes, he depicted an abandoned plow in a wheat field beneath an ominous sky. The birds move against the grain, still soaring out of the canvas.

GEORGES BRAQUE: THE LATE PAINTINGS -- At the Phillips Collection, opening Saturday, through December 12. Docent tours Tuesday, Thursday and Saturday at 2 begin this weekend.