LAST JUNE 5th was the hundredth birthday, however few of us observed it, of the great novelist this admirable biography celebrates; and as Dame Ivy has now been dead 15 years, our academic establishment might well look up from their James or their Joyce, and ponder: Here was the woman novelist of our century -- isn't she that for other centuries perhaps too? Even prima inter pares with de la Fayette, Austen, the Brontes, and George Eliot?

Certainly every element for an answer is there -- the elegance and the endless wit of her style, the formidable intelligence behind it, and, if you only judge by selected profundities, "a knowledge of people which would have been held to be impossible." All this the British critical establishment has been dealing with since her Brothers and Sisters in 1929; indeed, possibly all that still has to be professorily worked out is what could be called the Moral Basis comparisons.

In all her predecessors, characters assume that a fundamental human (or Divine) decency of some sort is what their lamentable transgressions trangress; in the Compton-Burnett world, the grim secret about the lawless appetencies of man is that in fact no such saving ideal operates or even exists to ennoble our sufferings, and the critical question is therefore whether her characters' appalling acceptance of evil's being universal, unregretted, largely unpunished, and perhaps not what we call evil anyhow, may be a vital part of the tremendous power of her thematic mythology.

In fact, "Much that I ought not to have done, I would do again," greed and treachery included, says the domestic tyrant in Darkness and Day: and as Hilary Spurling remarks, almost every one of the 20 novels "evolves around a protagonist of ferocious energy operating . . . with catastrophic consequences for the weaker or dependent members of his or her household."

This is not moreover just the routine Sophoclean "rage, envy, discord, strife,/ The sword that seeketh life," but parricide and pervasive sexual scandal, incest in particular. A father seduces his son's wife, the child she bears being therefore the old lecher's son and grandson, the son's half-brother, and the girl's brother-in-law as well as her son: "all these relations who are something else!" a character murmurs. And not only is sin always discovered -- and the discovery brazened out by the sinner -- but the baseness of human conduct is taken for granted, as simply how we do behave.

"'Bridget has done and suffered the traditional thing. As nearly as Oedipus as a woman can. He killed his father and married his mother. And she caused her mother's death when she was born, and married her father. The difference is, that she has not put out her eyes.'

"'Perhaps fashions have changed,' said Selina."

Small wonder if, in 1925, the "heartlessness" of her earlier Pastors and Masters, even if high-spirited and amusing, baffled and dismayed her friends. She was after all a severely formal late-Victorian spinster, known as placidly pouring tea for the chattering guests of the witty and fashionable decorator she shared a flat with, Margaret Jourdain. Why should this inarticulate contemporary of Lawrence, Joyce and Woolf turn out dialogue of the irreverent generation of Powell, Connolly and Waugh?

"'God always seems to me a pathetic figure, friendless and childless, and set up alone in a miserable way,' said Emily. 'Such a superior, vindictive, and over-indulgent one. He is one of the best drawn characters in fiction.'"

But the frivolous lucidity of this was a trial run for what Spurling admirably describes as the "compact prose, exquisitely balanced and refined" that Dame Ivy's dialogue soon became famous for. Her novels are almost wholly dialogue, and one aspect of her art is that every character's individual voice is as clear to us as his individual point of view, yet the very simple language is as polished as epigram. "To know all is to forgive all, and that would spoil everything." "The worst of things worth doing is that they are worth so little else." "My service is of a kind that cannot be paid for in money. And that means it is paid for in that way, but not very well." A suggestion that marriage would have led to a fuller life is answered by "I don't want the things it would be full of." Yet this 18th-century plainness (only seven words in 51 have more than one syllable) has a flexibility that can run from the urbane understatement of an epigram to the shrieks of tantrum, and has a standard level of politely savage family in-fighting that Auden once called "no quarter asked or given."

Spurling's biography of this strange and dauntng genius is a first-rate job, in scope as in detail. In particular she sets out, as one has to for us, that network of in-bred British intelligentsia cross-meshing the British class system, with every one of her immense cast clearly in his proper relationship and place. (Of course the British themselves need sometimes to be told too, e.g., that Jourdain's friends Soame Jenyns and Willie King "were connected through Bulwer Lytton on the Jenyns's side whose grandson married Byron's daughter Ada, wife to the eighth Baron King.") And throughout there is a practiced raconteuse's shower of anecdote and incident -- some familiar (it was Jourdain's sister Eleanor who saw those Versailles ghosts), but some, astonishing coincidence, even in a society where nearly everybody knew nearly everybody else (Dame Ivy's beloved brother Noel took over Rupert Brooke's rooms in Trinity, and they got their Fellowships together in 1913). Spurling has in fact produced a remarkable picture of a vanished day, and been wonderfully readable doing it. Several novels by Ivy Compton-Burnett have been newly reissued in paperback: Allison and Busby (distributed by Schocken Books) has published "Pastors and Masters," "Brothers and Sisters," "Men and Wives," "More Women Than Men," and "Elders and Betters," at $5.95 each. Oxford University Press has brought out "Manservant and Maidservant," also at $5.95. CAPTION: Picture, Ivy Compton-Burnett. Photograph Copyright (c) John Vere Brow