CHUTZPAH, AS YOU KNOW, my dear, is an amalgam of ambition and audacity which is only a hair away from foolishness. Paul Kresh, creative director of the United Jewish Appeal, admits he is ignorant of Yiddish but has attempted a biography of the present master of Yiddish prose, Issac Bashevis Singer. Chutzpah and friendship are hard to mix. I once heard Norman Mailer say to a reporter, "Why don't we stay friends? Forget your interview." Kresh confesses in his introduction, "There are aspects of almost every life that should not . . . be discussed publicly during the subject's lifetime," so he has tried to "walk the boundary between candor and simple decency." If he had crossed or waited, chutzpah might have carried the day. Instead, though Kresh mines valuable information about the sources of the Nobel Prize winner's magic, his endless plot summaries have the reader toiling toward the promised end with literary black lung and a whacking headache.

Kresh is at his best when dealing with his subject's early life as a starving roue in a doomed Warsaw, with his travels as a lecturer, and with life on West 86th Street over the past 12 or so years since Kresh became a friend. Unfortunately, the author's method of drawing continuous parallels between the work and the biography is such that the reader himself must keep separating the chaff from the grain.

Still -- Kresh can't resist some real chutzpah. Quoting Singer's nephew Maurice, repeating his uncle's advice, we have a few original aphorisms: "If a father wants to sleep with his daughter, why shouldn't he?" and "Nothing brings two men so much together as sharing the same woman." In a drizzling rain, the Yiddish writer cries out, "Who is He punishing? My only sins have been with women." And Kresh artfully shows his subject teasing a young couple on the subject of monogamy. "If you have one candle, with the flame from the candle you could light fifty others."

The most compelling part of Kresh's biography is the portrait of Singer's sexual curiosity -- alive and bounding even in his seventies. The dybbuks he writes about are not abstract. As a sad tale of his bizarre youth -- liaisons with dying widows, the girls of the writing club in Warsaw, landladies, young radicals (by one of these women he has an illegitimate son) -- makes clear, the dybbuks are a personification of his hunger to know the world. The contrast between this overpowering lust, his ego and a personal ethic of vegetarianism, fastidious for the welfare of parakeets and pigeons, brings us to a familiar contradiction.

Kresh agrees with the majority of critics, including me, who "find the endings of Issac's novels are seldom satisfactory." That final atonement and abasement are too pat -- only in his short stories will Singer leave the flirtation with the devil open. But his words about writing the short story ring hollow: "When you write a novel, especially a long novel, you are never the ruler of your writing, because you cannot really make a plan for a novel of say five hundred pages and keep to the rules . . . . While in a short story there is always the possibility of being really perfect." But there are novels -- Absalom, Absalom! or The Good Soldier, to name two -- which are as perfect as Singer's best stories.

What has cramped Singer's novels are his limitations. Writing about the Haskalah, the enlightenment which brought western thought into the Jewish ghetto, Singer says, "The Haskalah lacked the warmth and the exultation to really lift up the spirit. It could promise nothing but worldly gains . . . . There is not a single true Jewish work of art that glorifies the Haskalah and its movement, The true artist is never inspired by sociology or politics." This remark shows how far Singer has gone of late toward a personal notion of literature. Yet his greatest fictional creation, Gimpel the Fool, that holy simpleton decended from saints' tales and Tolstoy's Aloysha the Pot, is at last an exasperating nebechel whose suffering flesh is a rebuke, a political rebuke to a world bent on cruelty.

Singer's recent tales, while deeper in their sexual psychology and fantasy, have lost a certain dimension as the author begins to regard himself as the most interesting subject for fiction. The attack on the Haskalah is too easy. Singer's career is inconceivable without the opening of doors in the ghetto to western influences. Orthodoxy's most inspiring voice, Rabbi Joseph Soloveitchik, would never have been sent to Berlin for a degree if not for the tonic air of enlightenment in the recesses of Eastern Europe's rabbinate. Singer himself raises a constant litany to Spinoza -- an author he did not soak up at the table of mircle-working rebbes .

Despite a mass of fig leaves over some of these contradictions -- warts on the oracle, as it were -- enough of the naked Issac Bashevis Singer shows through to make Kresh's effort worthwhile. One particularly gets a sense of Singer in his youth, a tormented failure shadowed by his older brother, the world famous Joseph Singer, author of The Brother Ashkenazi, The Family Carnovsky and other fiction. The Magician of West 86th Street gives you one or two peeks under the trickster's table.