Mary Peabody (1806-87) shared her sister Elizabeth Peabody's passion for education and writing. Like all of the Peabody children, Mary was well educated by her mother, "Eliza," who taught school from their home and wrote poems on women's rights for the Haverhill Federal Gazette. Among Mary's more interesting experiences as a teacher was her post as a governess to a family in Cuba during the 1830s. There, she lived on a slave plantation and experienced for the first time the full force and horror of slavery.
In 1843, Mary, a thirty-seven-year-old teacher, married the prominent educator Horace Mann who was responsible for establishing normal schools in Massachusetts to train teachers to teach — including one in Salem which is today Salem State College. Horace Mann is considered the "Father" of American public education.
Mary raised their three sons while her husband served in the United States Congress and toured America lecturing on temperance, education, and abolition. Following Horace's sudden death in 1859, Mary briefly ran her own school in Concord, Massachusetts, before going to work for her sister Elizabeth at her new kindergarten in Boston — the first one in America.
Mary also helped her sister write the definitive Moral Culture of Infancy and Kindergarten Guide and was largely responsible for editing and publishing the newspaper The Kindergarten Messenger between 1873 and 1875. Mary Mann's literary output included a biography of her late husband, a Christian cookbook, and a romance set in Cuba and loosely based on her experience there. She also authored books on flowers and the plight of the American Piute Indian tribe.