Steegmuller's The Grand Mademoiselle (Farrar Straus- 1956) gave the American roading public a portrait of the contradictory figure of 17th century France's Anne-Marie Louise d'Orleans, Duchess of Montpensier, Chatelerault and St. Fargeau, Sovereign of Dombes, Princess of Joinville and Laroche-sur-Yon and Dauphiness of Auvergne -- and known simply as Mademoiselle. Her father Gaston was the younger brother of Louis XIII- and a sorry figure. His daughter was Europe's wealthiest princess, and her marriage was a matter of dickering in many courts until in her forties she took things, disastrously, into her own hands. Miss Sackville-West has saturated herself in the copious source material of an age when countless people of high estate left diaries, letters and records-so that Mademoiselle's own memoirs, patchy but -- when they came- revealing- form only a part of the whole rich background. And Mademoiselle emerges in all her contradictory personality, oddly uninformed, ignorant, arrogant, fearless, naive- and only too often, ridiculous. Her biographer leaves us no illusions about her, as she paints a child growing into maturity, with rarely realized ambitions, with a genius for involving herself- often melodramatically- on the wrong side. Her share in the plotting against Mazarin resulted in her exile. But then a great many key figures were in it with her, memorably the Condes, whom she now hated, and now worshipped. This is an extraordinary picture of France of the period, which spans Louis XIII and Louis XIV, for Mademoiselle travelled the length and breadth of her domains,rivalling Elizabeth in her royal progresses. It is a picture, too, of a court riddled with plotting and counterplotting, with extravagance, opposed by dire poverty around it. Miss Sackville-West sometimes seems to view her heroine obliquely, more in ridicule than compassion, and she certainly uses none of the more endearing qualities that Steegmuller employed. But in the handling of her fatal passion for Lauzun-another beastly cad (who with her father was really the only man who obsessed her), there is some degree of sympathy- and the reader accepts Mademoiselle with all her oddities, as a misused heroine. One could wish her biographer had stayed out of the picture- as a modern figure sitting in judgment; one could wish she had not thought it necessary to interject parenthetical equivalents from her French sources, as if to reenforce her skill as translator. But these are minor quibblings in what is an immensely valuable, scholarly and brilliant biographical feat.