Thomas Jefferson was the primary author of the United States Declaration of Independence and the third U.S. President. A polymath, he founded the University of Virginia and was a proponent of democracy, individual rights, and religious freedom. As President, he doubled the size of the nation through the Louisiana Purchase. However, his legacy is complex; while he wrote that 'all men are created equal,' he was a lifelong enslaver. His political philosophy, known as Jeffersonian democracy, emphasized agrarianism and limited federal government power, ideas that shaped the early American political landscape and continue to influence debates on American governance today.