Thomas Jefferson Thomas Jefferson was the third president of the United States. His terms lasted from the year 1801 to the year 1809. Jefferson was an American revolutionary leader as well as an influential political philosopher. Jefferson was among a group of the most brilliant Americans that resulted from the Enlightenment in Europe. Possibly one of the best writers during his time, Jefferson was the principal author of the Declaration of Independence. Jeffersonˇ¦s status as a Virginia aristocrat gave him the two most important things to become an educated man, which was a difficult thing to become during that time. Those two thi