TO HAVE SURVIVED the years from 1891 to 1976 and to have written alon the way 88 books including novels, short stories, memoirs, plays and even poetry, is an achievement of endurrance, intelligence and tact. Agatha Christie's autobiography, the second and supposedly the last posthunous publication of this prolific and secretive writer, is full of all three qualities. A personal philosophy and a good deal of insight there is. Scandal there is not. Revelation has no part in Dame Agatha's selective recollections, but lovers of the doughty Miss Marple and the crochety Hercule Poirot will recognize the occasional gleam in their creator's eye.

At the glowing heart of this long and gently rambling book are the years when Agatha Miller was growing up, beloved and protected by a leisure, comfortable Victorian family, at Ashfield House in the fashinable Devon resort of Torquay. Even discouting the roseate hue of memory, life was pleasant for the little girl attended by her kinldy "nursie" whose greying hair she decorated with ribbons and who put Agatha "into starched muslin [to] go down to the drawing room to my mother to be played with." No wonder the Victorians had an idealized view of childhood! To be fair, Christie does not ignore the lives of those whose labors made this pleasant existance possible. "One of the things I should miss most if I wer a child nowadays," she tells us around 1965, "would be the presence of servants. To a child they were the most colorful part of daily life."

The foundations of Christie's inexhautible and supremely lucid imagination were being laid in those days, as the little figure in her pinafore and carefully cultivated "sausage curls" peopled her world with imaginary kittens with whom she conversed at length. She derived her greatest pleasure from that solitary and long forgotten plaything, the iron hoop, which was "in turn a horse, a sea monster and a railway train" complete with ritual stations around the garden. Later in her childhood Agatha, for whom no formal education was xonsidered necessary or desirable invented a school that she filled with affectionate and minute detail, remainding us firmly of the ordered and disciplined virtues of that sunset era which ended so abruptly in 1914.

Once out of the nursery, Agatha's life was certainly a long and on teh whole a happy one. She shares with us her reflections on the progress of human nature and particularly her opinion that things are really not what they used to be. She also tosses out at intervals a good deal about how she came to be the queen of detective fiction.

She wrote her first story in a note book while langusihing with influenza as a young girl when she was "reduced to dealing myself bridge hands." The transition to detective fiction she attributes to that age-old spur, sibling rivalvry. Her sister Madge, a commisseur of detective stories, sconed Agatha's claim that she could write one too: "I bet you couldn't." That did it. "From that moment on I was fired by the determination that I could write a detective story . . . the seed had been sown." It was several years later when she first saw some of the characters in her first novel The Mysterious Affair at Styles sitting on a tram. A good deal of background for her polished poisonings was collected while working in a hosital dispensary during the first world war. (Eventually she took the Apothecaries Hall examination and qualified as a pharmacist.)

The war came and with it marriage to a young Flying Corps officer Archie Christie - from whence the famous name. Her only daughter Rosalind was born, and aprim rotund Belgain gentlemen also joined the family: Styles was finally accepted for publication and "though I did not know it," says Agatha. "Hercule Poirot, my Belgain invention, was hanging round my neck, firmly attached there like the old man of the seas."

Happiness and success seemed assured until one day Archie asked a divorce. "I supposed, with those words, that part of my life - my happy, successul, confident life - ended." Characteristically she dismisses the the breakup of her marriage in a single page. No details here. "There is no need to dwell on it," she says firmly, although combined with her own mother's death it resulted in a mental collapse surrounded by a blaze of publicity the discovery of her abandoned car, her probable amnesia and her reappearance in a hotel registered under her husband's lover's name. Although she never refers to the incident directly, she does go on to mention that form this time (1926) dated her hatred of the press. "I had felt like a fox, hunted, my earth dug up and yelping hounds following me everywhere." She later congratulates herself on the success of the elaborate arrangements made to keep secret her second marriage to the archeologist Max Mallowan, a man considerably her junior, but the book gives us little sense of her fame or of why such extremes were necessary.

In fact, Chritie's worldwide fame and her public stature intrude amazingly little into the quiet, literate tenor of her book. She is more explicit, howere, about her material success, taking a feisty pride in earning her own living, in buying and refurbishing houses, traveling extensively and in giving various of hr prodigious out-put to friends, relatives and good causes - her only grandson Matthew reaped a windfall when she gave him the copyright to the record-breaking play "The Mousetrap."

Christie regarded herself as an artisan of the writing trade. "Be a wheel-greaser if you can't drive a train" read a motto on her wall. She is full of literary humility. "If I could write like Elizabeth Bowen, Muriel Spark or Graham Greene, I should jump to high heaven with delight, but I know that I can't." She defines her informal technique of autobiography: "It is as though one went to a great trunk full of junk in the attic and plunged one's hand into it and said, "I will have this - and this - and this." She says later, somewhere in the middle of her account of life in the Middle East with Mallowan, "I have decided no to tidy this book up too much. For one thing I am elderly . . . I am perhaps talking to myself - thing one i s apt to do when one is a writer."

Despite her disclaimers, Agatha Christie was a modest, industrious and low-keyed genius. Profoundly shy all her life (she was once turned away from a party in her honor because she was too shy to identify herself), she disliked change, airplanes, smoking, the feet of birds and, most of all, the smell of hot milk. She takes us with her into the calm of old age and describes herself at 75 "comfortably waiting in Death's antechamber . . . enjoying myself." Here as elsewhere she under estimates hersel. She published a further 13 novels while she was "sitting in the sun, gently drowsy" and saw some 400 million copies of her books sold sto innumerable fans. This endearing volume will transform many fo them into her friends.