FAMILY AND FRIENDS. By Anita Brookner. Pantheon. 187 pp. $13.95.

ADMIRERS OF Anita Brookner's four previous novels will be both gratified and startled by Family and Friends. Gratified, that is, because Brookner's salient characteristics are once again much in evidence: her extraordinary sensitivity to the subtleties of human relationships, her calm analysis of life's disappointments, her wry and ironic sense of humor, perhaps above all her rich, resonant, astute and penetrating prose. But startled, too, for without writing a page more than she has in the past Brookner has nonetheless broadened her territory immensely; where previously she painted exquisite if somewhat rarified miniatures, in her fifth novel she has created a panorama.

It is a panorama of family life. The Dorns are Eastern European, probably Jewish; they left he Continent between the wars and live now in London, in a condition of great comfort if not opulence. There are five of them: Sofka, the mother, Frederick and Alfred, her sons, and Betty and Mimi, her daughters. Her husband, whose name is unnecessary to the tale, "is absent, gone before, dead, mildly disgraced." They inhabit a "world of weddings and marriages," and Sofka is their undisputed leader:

"She is a shy woman, virtuous and retiring, caring only for her children, but determined to fulfill her role as duenna, as figurehead, as matriarch. This means presentation, panache, purpose and, in their train, dignity and responsibility; awesome concepts, borne permanently in mind. Like a general on the evening of a great campaign, like an admiral setting a course for his fleet, Sofka looks to the family fortunes and plans her performance accordingly. She surveys her children, is proud of them, trembles for them. The tremor conveys itselto her hand, and a tiny drop of Madeira gleams on the polished wood of the little table. 'Mama,' says little Alfred. 'The car has come round.' "

It has come round to deliver the family to yet another wedding, "a wedding in the old style, with something of a feeling for the old country." The life of the family is constructed around weddings: not merely the staging of them but, far more important, the scheming and plotting and arranging of them, the sleepless worrying over them, the triumphs and defeats that they represent. At the weddings photographs are taken, formal photographs in which each member of the family presents his or her particular facade to the world, yet in which a certain truth can sometimes be glimpsed -- photographs that Brookner uses with exceptional subtlety and ingenuity as landmarks in her narrative.

YET TO CALL Family and Friends a narrative is not entirely accurate, for it is less a tale than a meditation. It wanders back and forth between past and present seemingly without method, but Brookner always knows where she is going: to locate the truth about each of the five Dorns, to give them to us as they see themselves and as they actually are. This she accomplishes by moving back and forth among them in a leisurely and measured manner, concentrating her full attention on each for a time before moving on to the next.

They divide into pairs. On one side are Frederick and Betty, the prodigals. As a young man Frederick "is so charming and so attractive that women forgive him his little treacheries"; he moves casually from one romance to the next and devotes as little time as possible to the family business, yet is untroubled by either guilt or criticism, which his indulgent family spares him. As for Betty, she believes that "her mission in life is to be a woman who prevents men from staying with their virgin loves, and she is eager to embark on this career." She is "so violently single-minded that she will flirt with herself if there is nobody else immediately available," and is "one of those naturally unfair women who rule by bouts of ill-humor and whose sudden unpredictable changes of mood bring about relief, gratitude, and a general lightening of the atmosphere."

While Frederick and Betty fly the coop, sybarites in search of utter satisfaction, Mimi and Alfred stay home. They "stand for those stolid and perhaps little regarded virtues of loyalty and fidelity and a scrupulous attention paid to the word or promise given or received." Mimi, who as a very young woman was defeated by Betty in the competition for a man, mourns this loss in spinsterhood: "Somehow she knows, correctly, that without this false start, this disgrace, this defeat, she could have taken her chance like any other woman." Alfred, who as a boy yearned for the life of the mind, instead runs the family business and aches for "that life of risk and impropriety which has been his temptation, his fantasy, and his promised reward ever since he discovered, to his infinite regret and relief, that the farther shores of the real world were not within his compass."

THUS THE division of the siblings is therefore not quite so clear-cut as we at first imagine it to be, and as the story gradually unfolds it becomes even less so. The two prodigals ultimately reveal themselves to be considerably less adventuresome than they imagined, while the two who abide by rules and conventions attempt to reach beyond the confines of family to fulfill their own secret dreams. Even Sofka, that pillar of convention, finds herself torn:

"There have been telephone calls to Betty every Friday evening, and when she comes away from the telephone Sofka allows a small smile to play round her lips. Does she secretly rejoice in this outrageous daughter who has the courage to break with the conventions? Does Sofka like the bad rather than the good in her children? If Mimi and Alfred are the alleged and established good son and daughter, deferred to for their very beautiful qualities, does Sofka nevertheless contemplate with a private delight Frederick's dissolute charm and Betty's nerveless insolence? 'Mama, Mama,' wheedles Betty on the telephone. 'Don't be cross with me, little Mama.' And she puts a kiss into the receiver which Sofka hears with a smile."

Of course, because within Sofka too there are yearnings for the unconventional. She has devoted herself to the most scrupulous observance of the rules: "Her own life has been spent in avoidance of the fatal passion and she has not, she thinks, been wrong. . . . She knows only what is appropriate, suitable, in order." Yet the fascination and secret pleasure with which she considers the mischief of her errant pair belie another side of her, a side that acknowledges the appeal of impropriety even if she can only experience it vicariously. Like the father in Peter Taylor's great story "The Gift of the Prodigal," she privately condones behavior by her children that she could never permit in herself.

But quite apart from the appeal of the unconventional, Sofka winks at the misbehavior of her children because they are hers. Family and Friends may be in some measure about a family coming apart, but it is also about the loyalties that make it endure, that allow it to countenance behavior by its own members that it would condemn in others. In Brookner's clear-eyed, compassionate and tolerant view, all the mistakes and misbehavior of the Dorns are subordinate to their identity as a family; even apart, even with the anchor of Sofka at last removed, they remain together in spirit, bound by family. In exploring this universal truth, Brookner has written a novel more expansive and inclusive than any of its four predecessors, and she displays ample reserves of a quality that can only be called kindliness. Family and Friends is a fine and heartening book.