One of the most prolific American political essayists, lecturers, and religious philosophers of the nineteenth century, Orestes A. Brownson in his early writing and lecturing career, particularly in his role as editor of the Boston Quarterly Review (1838-1842), worked at the center of many debates concerning theology, Jacksonian politics, and proto-Marxian labor theory. He became notorious during those same years for his tendencies to change his religious affiliation and his political positions. Following his 1844 conversion to Roman Catholicism, however, he turned his considerable rhetorical skills toward the cause of promoting his new religion, which he hoped would eventually become the dominant religion in the United States, and remained a Catholic for the rest of his life. Although he was an early associate of Henry David Thoreau and Ralph Waldo Emerson and a dominant figure in early Transcendentalism, his conversion to Catholicism--surprising to his associates--led him to a career...