If Ralph Waldo Emerson represents what literary historians call the New England "Renaissance," Emerson's fellow Transcendentalist Theodore Parker represents what might be called the New England "Reformation." Both men started their careers as Unitarian clergymen, but Emerson left the ministry to become a lecturer, essayist, and poet, while theological themes, often overt in his early writings, over time became implicit. Parker also became a popular lecturer and important essayist but never changed his profession; in the 1850s he was one of the most prominent preachers and theologians in the United States. Again, although Emerson sympathized with reform, was respected by reformers, and even inspired others to become reformers, he confined himself to a minor role in the many reform movements of his day. Parker helped lead the crusades for church reform, alleviation of urban poverty, woman's rights, and abolition of slavery. He also emerged as an important theorist...