After his term in office, Jefferson eventually reconciled with Adams and they shared a correspondence that lasted fourteen years. As president, Jefferson pursued the nation's shipping and trade interests against Barbary pirates and aggressive British trade policies. Starting in 1803, he promoted a western expansionist policy with the Louisiana Purchase which doubled the nation's claimed land area. To make room for settlement, Jefferson began the process of Indian tribal removal from the newly acquired territory. As a result of peace negotiations with France, his administration reduced military forces. He was re-elected in 1804, but his second term was beset with difficulties at home, including the trial of former vice president Aaron Burr. In 1807, American foreign trade was diminished when Jefferson implemented the Embargo Act in response to British threats to U.S. shipping. The same year, Jefferson signed the Act Prohibiting Importation of Slaves. Jefferson was a plantation owner, lawyer, and politician, and mastered many disciplines including surveying, mathematics, horticulture, and mechanics. He was also an architect in the Palladian tradition. Jefferson's keen interest in religion and philosophy led to his appointment as president of the American Philosophical Society. He largely shunned organized religion but was influenced by Christianity, Epicureanism, and deism. Jefferson rejected fundamental Christianity, denying Christ's divinity. A philologist, Jefferson knew several languages. He was a prolific letter writer and corresponded with many prominent people, including Edward Carrington, John Taylor of Caroline, and James Madison. In 1785, Jefferson authored Notes on the State of Virginia, considered perhaps the most important American book published before 1800. Jefferson championed the ideals, values, and teachings of the Enlightenment. Since the 1790s, Jefferson was rumored to have had children by his sister-in-law and slave Sally Hemings, known as the Jefferson-Hemings controversy. A 1998 DNA test concluded that one of Sally Hemings's children, Eston Hemings, was of the Jefferson male line. According to scholarly consensus, based on documentary and statistical evaluation, as well as oral history, Jefferson probably fathered at least six children with Hemings, including four that survived to adulthood. After retiring from public office, Jefferson founded the University of Virginia. He and John Adams both died on the same day, July 4, 1826, which was also the 50th anniversary of U.S. independence. Presidential scholars and historians generally praise Jefferson's public achievements, including his advocacy of religious freedom and tolerance in Virginia, his peaceful acquisition of the Louisiana Territory from France without