Born into Boston's elite and trained at Harvard University as a Unitarian minister, Samuel Joseph May rejected his upbringing to become a central figure in the antislavery and antebellum reform movements. With this intellectual biography, Donald Yacovone has written the first modern account of May's life. May's friendships with William Ellery Channing, William Lloyd Garrison, and Ralph Waldo Emerson, and his work in the major crusades of his era make his life a virtual history of antebellum religion and reform. Though his ideals threatened his clerical career and his family relationships, he feverishly devoted his life to the abolitionist, peace, and temperance movements, education reform, and women's rights. The Liberal Persuasion was an intellectual movement that arose out of New England during the golden age of the Unitarian faith. May was the leading representative of this humanist ideology that rejected slavery and racial prejudice, advanced free religious inquiry, promoted republicanism and a generous interpretation of civil liberties, supported the emancipation of women, and defended the social and political rights of the working classes. Author note: Donald Yacovone is a Research Associate at the Black Abolitionist Papers Project, Florida State University.