MARY P. RYAN is John Martin Vincent Professor of history at Johns Hopkins University. Mysteries of Sex returns to - and fundamentally reinterprets - the theme of her first book, Womanhood in America (1975). Ryan's other books include Civic Wars: Democracy and Public Life in Nineteenth Century America; Women in Public: Between Banners and Ballots, 1825-1880; and Cradle of the Middle Class: The Family in Oneida County, New York, 1790-1865.