John Locke had such a profound influence on Thomas Jefferson that he may be deemed an honorary founding father of the United States. He advocated the natural equality of human beings, their natural rights to life, liberty, and property, and defined legitimate government in terms that Jefferson would later use in the Declaration of Independence. Locke's life and works are discussed, and the lecture shows how he transformed ideas previously formulated by Machiavelli and Hobbes into a more liberal constitutional theory of the state.