"O My America!" tells of an extraordinary man who has a lifelong and unholy alliance with "the idea of America." It is Johanna Kaplan's first novel, written with an authority that seems born of a deep affection.

Her protagonist, Ez Slavin, emerges from the hubbub of the immigrant's Lower East Side to become a man of letters, social critic, teacher, Don Juan and iconoclast. Over the years his involvements, both intellectual and amorous, reflect the political and cultural kaleidoscope of America at mid-century. Although often faulted for throwing himself at the idols of the cave, Slavin is nonetheless compelled to live out the question, "How should free men conduct their lives?" The women he beds and marries are less mates than embodiments of his ever-broadening and impassioned ideals: a Jewish social reformer, a midwestern novelist with an "authentic" American intelligence, a self-styled bohemian and a simple mountain girl. But his only enduring relationship is with the continent itself.

The novel opens with an account of Slavin's death. It closes with what is surely a work of love, a coda for a great man's life, orchestrated by his oldest daughter. Much of the novel, in fact, is told from the point of view of Merry Slavin. In taking on the obligations attending her father's death, she reshuffles his past -- and finds herself reliving it. She also finds herself trying to come to grips with what her father once called the "grasping, corrosive, destructive force" of families, her own in particular.

Of Slavin's six children, Merry is the only one who understood him. The others either loved or hated him, but Merry loved, hated and understood him all too well. For Merry, who is painfully like her father, is aware that she lives in the shadow of his peculiarly moral passions:

"Merry . . . felt a rage that rose up and lodged in her mouth with the taste of a bloody toothache. Ez didn't care how he lived, he didn't care what he ate. . . But it was not a matter of principle; he really just didn't care, and in his not caring, any small pleasure or sweet comfort that could be wrested from life was made to vanish. He has taught me nothing but austerity, Merry thought bitterly. . . ."

Kaplan knows how to bare character through the subtleties of speech -- most of "O My America!" is dialogue. Her ear is precise and often merciless; not only characters but entire generations and cultures are allowed to unwittingly convict themselves. There are times, however, when the novel seems burdened with talk. Especially wearying is Ffrenchy, the representative hippie, for no matter how accurately one captures the cadences of stoned rattling, it remains, well, stone rattling.

The emphasis on spoken language also overwhelms the sort of description that Kaplan does well:

"From the Roizmans' fifteenth-floor apartment on Central Park West, from their high, wide windows, the whole autumn city -- full red and gold trees and misty buildings, blind towers and light, vaulting bridges, ridged roofs and shaded windows, buses and cars that stopped and started as far away as Madison Avenue, and traffic lights that blinked and changed beyond a river and among invisible streets, probably Queens, the sense of bustle and removal from bustle -- all of it, all of it flew before Merry in the high thin golden light of a childhood dream.

Such description is as telling of character as is faithfully recorded speech, for it suggests the intimate ties between people and their land (or city) scapes.

"O My America!" is a shrewd and generous novel. It brings to life a family, a culture and several generations, but most of all it brings to life an American mensch. If the novel is flawed, it is, like Ez Slavin himself, flawed in the direction of excess: excessive talk, excessive irony, execssive rage, excessive love.