"Margaret Fuller," by Megan Marshall Margaret Fuller died on July 19, 1850, in a shipwreck off Fire Island. In her intellectual prime and at the height of her influence as a social reformer, she was returning home from Europe with her Italian husband and their child. A major advocate for the rights of women, Fuller had left the United States in 1846, just a year after the publication of her influential book, "Woman in the Nineteenth Century," which both Susan B. Anthony and Elizabeth Cady Stanton cited as an inspiration. Having accomplished her mission, as Megan Marshall puts it in this new biography, "to meet the writers and radicals whose work she'd admired from afar and test their minds in conversation," Fuller was coming home to the United States, having flagrantly acted out the freedoms she demanded as every woman's right. Houghton Library, Harvard University Daguerrotype of Margaret Fuller, 1846. A New American Life By Megan Marshall Illustrated. Houghton Mifflin Harcourt. $30. "Margaret Fuller: A New American Life" returns Marshall to the Boston Brahmin salons of her earlier and deservedly praised biography, "The Peabody Sisters," whose three subjects, Elizabeth, Mary and Sophia, campaigned with Fuller against the sexist double standards that starved women's intellects and denied them agency in any but the domestic sphere. It was at Elizabeth Peabody's West Street bookstore that Fuller conducted many of her celebrated "conversations," unorthodox gatherings of female intellectuals who looked toward "a changed world, with women as powerful as men." Most of those who conversed about women's rights ended by sacrificing their noble ideals to the comforts of marriage. Not Fuller, who walked her talk, endorsing "scandalous living arrangements" over what she termed a "corrupt social contract" that, Marshall adds, "cheated wife far worse than husband." From the time he perceived his daughter's genius, Fuller's father, Timothy, a congressman from Massachusetts, determined to push his firstborn "as near perfection as possible." He lavished an education as fine as any boy's on Margaret, who was reciting in Latin by the age of 6 and who, under a "torrent of criticism," mastered her father's greatest lesson: "Mediocrity is obscurity." As Marshall observes, Fuller's success in wooing her father's attention away from her much prettier mother by gratifying his need for an "intellectual consort" inspired her later headlong rushes into one feverish cerebral consummation after another. A template for love based on a brilliant outspoken female sparring with a man of less acute intelligence was likely to yield an anguished romantic career. In the mid-19th century, even a high-minded man who supported women's rights usually opted for a domesticated wife, preferably one prettier than Fuller. Ralph Waldo Emerson, one of the pre-eminent thinkers with whom she would spend her life in discourse both on and off the page, judged her emotionally voracious, looking for an "absolute, all-confiding intimacy between her and another." A sure-footed biographer, Marshall admits to devoting disproportionate attention to a subject that was catalytic to Fuller's emotional as well as intellectual development, the "circle of young "lovers" who were drawn to the flame of her intelligence" and were invariably left blistered, eager for gentler company. No one likes a conceited genius, and Marshall seems to know that she can't hold her readers for long without countering the arrogance Fuller's accomplishments inspired. How better to summon sympathy than to highlight the romantic disappointments that attended the bluestocking's homeliness and lack of social grace? Fuller may have been sharing the opinion of others when she observed that "there was no intellect comparable to her own" - not in the United States, anyway - but even friends who railed against the highhanded superiority of "Queen Margaret" relented in the face of her often abject loneliness. Kathryn Harrison is writing a biography of Joan of Arc. Her most recent book is "Enchantments," a novel.