A Generation in a Rift : The conflict between who one is and who one has been made : THE BOOK OF KNOWLEDGE, <i> By Doris Grumbach (W.W</i> . <i> Norton: $22; 248 pp.)</i>

At the end of Doris Grumbach’s riveting new novel, “The Book of Knowledge,” the narrator tells us that “It is true of all human beings that they are dualities, two persons” and that the “lifelong conflict” between these two persons is often a “bloody warfare . . . to be who we are and not what we have been made.” No generation illustrates this observation better than the one Grumbach depicts in her wide-ranging and audaciously omniscient narrative, a generation fathered by those who served in the World War I, a generation who experienced the Great Depression during their formative years, a generation who would come back after the second World War to a society to which the word outing meant just another picnic with the Joneses.

We meet her four main characters in childhood that “long, happy fabric of time,” not yet “broken by the fierce rips of adolescence.” The Flowers children, Kate and Caleb, live permanently in the seaside town of Far Rockaway with a rather dreamy war-widowed mother who presents them with an idealized portrait of their dead father and whose failing hearing allows her to miss the nuances of her children’s fantasy life. This secret life and their mounting physical attraction remains “Edenic” even into “early adolescence.” Into this summer resort arrive two families from “the City.” The fathers are both successful brokers in a market that was even hotter than the city streets their families were escaping.

The Flowers children become friendly with Lionel Schwartz, a shy, pale boy and Roslyn Hellman, a fierce-spirited and dark-haired girl, who becomes the leader of their group. Roslyn invents a club for them, which she dubs “the Talkies.” She takes the name from the New York Times’ description of “a new kind of motion picture.” In this summer of 1929 the children play and compete, as both the sea and croquet prove dangerous.

By the summer’s end “Lion” and Roslyn return to the comforts of their upper-class Manhattan lives that will soon be ripped away from them forever by the savage force of the Crash and the ensuing Great Depression. Kate and Caleb Flowers remain in the relative security of their life in Far Rockaway. The sister and brother reach a peak of intimacy, sexual and emotional, that will haunt them the rest of their lives.

After this introduction, Grumbach is free to range, presenting highlights in the lives of each against the history of the times. We next meet Roslyn Hellman the following summer. She is sent to Camp Clear Lake. “ ‘You’re lucky to be getting out of the hot city,’ her mother said. . . . ‘No polio worries. Think of us sweltering here.’ ” “Here” is now Brooklyn, to which the family has been deported after the father’s fall from grace. An aunt has provided the funds to allow the Hellmans a summer’s reprieve from their daughter’s dissatisfaction and demands to be taken back to “the City” (when it is capitalized it is Manhattan) to see movies they can no longer afford. At Camp Clear Lake, Roslyn brings to mind the young fearless Maggie Tulliver of “The Mill and the Floss,” just as Grumbach’s third-person narrator, omniscient, ironic and wise, has glimmers of a contemporary--and surprisingly laconic--George Eliot.

Roslyn’s dauntless spirit prevails into young adulthood. She serves as a Wave in World War II. Afterward she dreams of a publishing career and envisions a female society that she will never realize anymore than she will find physical fulfillment.

As early as the summer of 1930, at camp, she will learn that love “was a well-camouflaged phantom, an avid, contemptuous, sneaky mob member, a guerrilla fighter prepared to destroy the natural peace of her heart, always secretly at war with her contentment. Most terrible still, when her body betrayed her, she was taught that it was a wild child . . . never, never obedient to her will.” That summer she is told by Fritzie, the counselor she has fallen in love with, that “You don’t really love me. You’re a silly kid with a crush. Everybody gets them sometime or other.” After all, “Girls don’t love girls.” Well, they do at Camp Clear Lake but it is part of Roslyn’s destiny not to find companionship among those women of her time who, quite quietly, ever mindful of society, did.

In fact, unknown to her, both her old friend Caleb Flowers and Lionel Schwartz--who she bumps into occasionally--re-meet in college and fall heads over heels in love with each other. They will have one glorious year of love and sexual fulfillment before what the world expects of him overshadows Caleb.

Meanwhile, Caleb’s sister Kate (physically Lionel reminds Caleb of Kate) stays in Rockaway tending their ailing mother. Mrs. Flowers is described with the concise power that often rises to epiphany in this novel: “Silent as falling snow, she sank into somnolence and weight.” Tending her mother, Kate waits for the brother and the incestuous love that will never return.

The love that each of these characters finds or searches for is a love that their society condemns. It is through their inability to express their true natures--or to see it mirrored in others--that each is undone. Only the once shy, fragile Lionel was really ready to make the plunge into selfhood, but the force of history itself became his undoing.

The stories of Roslyn, Lionel, Caleb, Kate and their families are told and interwoven with great irony, subtlety and beauty. No one at any time escapes the conflict Grumbach presents, the duality between what a person is and what others would have a person be. Fifty years after the last World War society certainly (if begrudgingly) allows its children much more freedom. And it is from this vantage point that we can see that in “The Book of Knowledge,” with masterful conciseness and with her own unique haunting force, Doris Grumbach, has brilliantly delineated the tragedy of an entire generation.