DIARIES have been essential to historical research focusing on the experience of American women. Catherine Clinton relied heavily on the diaries and journals of upper-class women for her study of "The Plantation Mistress: Woman's World in the Old South." John Mack Faraghar drew from the journals kept by 800 men and women who settled in the far West for his volume "Men and Women on the Overland Trail." Laurel Thatcher Ulrich based her Pulitzer Prize-winning book, "A Midwife's Tale," on the diary of one woman - Martha Ballard - who lived in Hollowell, Maine, in the early years of the republic. As these historians have shown, diaries kept by women unravel the threads in the fabric of American life, revealing not only the pattern of a woman's experience but also the texture of the society in which she lived - the class structure, business relations (informal as well as formal), the political system (especially at the local level), and the place of education, religion, and medicine. The tendency of women to use the diary as a tool for self-examination and a means to establish a sense of identity and self-worth suggests the importance of this kind of historical record in conveying manners, morals, attitudes, and values. This new edition of "The Civil War Diary of Sarah Morgan," edited by Charles East, is a superb example of the genre. (An abridged version, edited by Warrington Dawson, Morgan's son, was published in 1913 under the title "A Confederate Girl's Diary.") A young, single woman from an upper-class family in Baton Rouge, La., Sarah Morgan recorded the events in her own life and the events of the war that shaped her life from January 1862 through June 1865. In the introduction to this volume, East declares, "Sarah Morgan compels our attention. In some respects she is exactly who we expected her to be - the young girl wearing the Confederate flag on her bosom, lamenting (as many Southern women did) her inability to take an active part in the fighting. But in many others she is her own person: intelligent, proud, sure of her place but unsure of her self, fiercely independent. Above all, she is blessed with an observant eye and that most wonderful and indispen sable thing for a diarist, a questioning nature." As an editor, East has done a fine job of introducing his subject and directing the reader's attention to some of the principal themes: the patriarchal character of Southern society in the antebellum period, the centrality of sibling relationships, and the importance of education for women in that society as a means of preserving status. He points out the tensions in Sarah's own thinking with regard to the place of women, citing on the one hand her pride in intellectual achievement yet, on the other, her insistence that a husband be superior to his wife. East also notes the transition in Sarah's thinking with regard to the war. Like her father, Sarah initially opposed secession, but as the Union army moved into the South, destroying her home and forcing her to flee with her mother and sister to live with her half-brother in New Orleans, then under Union control, her support for the Confederacy swelled into a passion. The decision to seek asylum in New Orleans in April 1863 was made out of desperation. On March 31, Sarah explained: "We have tried in vain to find another home in the Confederacy. After three days spent in searching Augusta, Gibbes [another brother] wrote that it was impossible to find a vacant room for us, as the city was already crowded with refugees.... We next wrote to Mobile, Brandon, and even that horrid little Liberty ... and every where received the same answer - not a vacant room, and provision hardly to be obtained at all." The Union strategy of fighting a war of attrition was i ndeed successful. The family, though clearly upper-class, was impoverished. Their home in Baton Rouge had been the only concrete source of wealth; the remainder of the family's resources lay in unpaid debts. The Morgan women had no real choice but to accept the offer of shelter from Judge Philip Hicky Morgan, the eldest son, who had assumed the position of patriarch when his and Sarah's father had died in 1861. The fact that Philip was a Unionist did not influence Sarah's affection and respect for him. "Politics cannot come between me and my father's son," she wrote on Jan. 23, 1863. "What he thinks right, Is right, for him, though not for me. If he is for the Union, it is because he believes it to be in the right, and I honor him for acting from conviction, rather than from dread of public opinion." Philip, in turn, respected their decision to support the Confederacy and refrained from flaunting Union victorie s while keeping them informed of the progress of the war. Sarah's experience of living in Union territory provides an unusual perspective on the last two years of the war. She describes the double agony of learning of the defeats at Vicksburg and Gettysburg, of the surrender of Lee at Appomatox, and having to face the victorious foe in daily encounters. She writes, too, of her struggles with guilt at having taken an oath of allegiance to the Union, required of all who crossed the line from the Confederacy. The war dominated Sarah's life but so too did the attitudes and values, manners and morals, of Southern society. Despite her exceptional intelligence and determined independence, Sarah was inevitably a product of the socialization process. She was, for example, preoccupied with appearances and the superficial rules of propriety. While denying any interest in the several men who showed her particular attention, she carefully recorded their visits, evaluated their characters, and (perhaps unintentionally) led them on - a pattern of behavior that was apparently common in the antebellum South. A capable seamstress and knitter of socks (skills she employed in the service of the Confederate army), she was, like other single women of her station, without any training in basic household management. And she was, without apology, a supporter of slavery - again, a common attitude among young women who did not yet have the responsibility (married women called it the "burden") of managing the household slaves. Sarah Morgan's diary is not only a valuable historical document. It is also a fascinating story of people, places, and events - told by a wonderfully talented writer.