"expose Mormonism," but Pratt would later publish a statement in the Nauvoo Expositor to deny this claim. Pratt soon returned to the church and denounced Bennett. Van Wagoner cites a letter written by Pratt's brother Parley P. Pratt which said that Orson was a part of the church and that Bennett's book, The History of the Saints (1842), was written solely to get vengeance on those who had excommunicated him and barely worth mentioning. Pratt wrote a postscript to his brother's letter: "J.C. Bennett has published lies concerning myself & family & the people with which I am connected". Smith and Pratt directly discussed Pratt's wife, with Smith stating to him, "She lied about me: I never made the offer which she said I did," after which Joseph suggested he divorce Sarah and start a new family. Pratt did not divorce Sarah at that time, though one source does report that Orson came to believe that Sarah had lied about Smith's proposal. This event would impact the couple for the rest of their lives; they eventually did divorce, though decades later. Sarah secretly encouraged her children not to believe in Mormon teachings. She and her son, Orson Pratt Jr., eventually apostatized from the church. Writer, historian and philosopher While in Illinois, Pratt acted as an instructor of mathematics at the University of Nauvoo. In Utah, Pratt's strong skills in analysis and writing led Young to assign him to produce sermons and pamphlets dealing with religious topics. Pratt wrote sixteen pamphlets in defense of LDS Church doctrines, drawing on the works of Joseph Smith and his brother Parley P. Pratt. These include "Divine Authority, or the Question, Was Joseph Smith Sent of God?" in 1848 and "Divine Authenticity of the Book of Mormon" in 1850 and 1851. His pamphlet "An Interesting Account of Several Remarkable Visions" was the first published account of the First Vision and included a list of beliefs that is similar to Smith's 1842 "Articles of Faith". In "Absurdities of Immaterialism", Pratt defended the Mormon doctrine of materiality, with reference to science, philosophy, and theology. As part of his system of Mormon theology, Pratt embraced the philosophical doctrine of hylozoism. Although these materials were primarily used in the mission field, Pratt was also a church spokesman on the topic of plural marriage. At a special conference in Salt Lake City in August 1852, Pratt publicly preached a sermon