Principal author of the Declaration of Independence (1776), third president of the United States, and the American founder most identified with the agrarian-republican strain of Classical Liberalism. Jefferson took John Locke's language of natural rights — life, liberty, the pursuit of happiness — and fixed it in a political charter that has shaped American self-understanding ever since. He was also a gifted architect, amateur scientist, university founder (Virginia), and prolific correspondent whose letters are a continuous Enlightenment seminar on politics, religion, and natural history.
His political vision prized local self-government, a broadly diffused property-owning citizenry (he imagined a republic of yeoman farmers), strict limits on federal power, and vigilant separation of church and state. He was genuinely sympathetic to the The French Revolution — a sympathy that led him into some of his worst political misjudgments — and he corresponded warmly with Thomas Paine. He was also, unforgivably, an enslaver. The contradiction between his writing on liberty and his lifelong ownership of human beings (including the long sexual relationship with Sally Hemings now confirmed by DNA) is the central difficulty of his legacy and of American liberalism itself.
As president he doubled the nation's territory with the Louisiana Purchase, a stretch of constitutional authority he himself doubted. His later years at Monticello produced a remarkable correspondence with his rival-turned-friend John Adams — two old men, dying on the same Fourth of July in 1826, arguing out the meaning of what they had helped make.