IN THE EMERGENCY WARD OF THE MIND: Review

In her most recent works Miss [Iris Murdoch] introduces a hero-demon, a charismatic figure who goes, or tries to go, all the way to some emergency ward of the mind where great ideas and the word salads of schizophrenics lie side by side. And indeed, like schizophrenics, her people do hear voices, the voices of the great characters and eccentrics in the history of fiction: Don Quixote, Dr. Faustus, Mr. Casaubon in ''Middlemarch,'' Dostoyevsky's Raskolnikov and Kirillov in ''The Possessed,'' who says that he will kill himself out of enthusiasm. They hear the voices of Captain Ahab and Paul Valery's Monsieur Teste, who complains of ''syllogisms debased by agony.'' They hear the eurekas, expostulations and apostrophes of Hans Castorp and Mynheer Peeperkorn in ''The Magic Mountain,'' of Mr. Ramsay in ''To the Lighthouse,'' of Stephen Dedalus and of Louis-Ferdinand Celine's splendid scoundrels. The other characters are ambivalent about [Marcus Vallar]. Jack, a painter with an ''infertile facility,'' grudgingly admires him. He teaches Marcus, who is already a celebrated mathematician, to paint, but in spite of the fact that Marcus's canvases are bought and admired, he abandons painting because it has led him ''to the brink of a void'' that turns out to be, in his opinion at least, the wrong void. Gildas, a priest, is jolted out of his faith and his vocation by Marcus, who sometimes injures people in a reckless flexing of his charisma. In the same way Marcus seems to have ''cursed'' Patrick, an Irish poet who has taken to his bed to await what anthropologists call a voodoo death. Patrick is terribly emaciated, in ''a deep terminal coma'' brought on by no medically ascertainable causes. Miss Murdoch is mischievous about philosophers. She puts Marcus into the toilet for hours at a time. [Ludens] is shocked to see him wearing running shoes, a running commentary, so to speak, on philosophy's concession to fashion and haste. Marcus has got rid of all his books, as if to suggest that he's gone beyond the primitive business of printed matter. He has also begun to make gnomic remarks. He says that he ''felt ready to return to the philosophers, but only, as he put it, to learn from their illusions and place his feet upon the rubble of their arguments.'' He observes that ''ultimately morality must be discovered to be a superficial phenomenon.'' ''One has,'' he says, ''to purify oneself at every step.'' Toward the middle of the book he says, ''I must now rest from multiplici