John Locke (1632-1704) was an English philosopher and a major influence upon the Founding Fathers. A founder of British empiricism with an unabashed faith in the natural sciences and the rising middle class, Locke embodied the principles of the Enlightenment.
In his Essay Concerning Human Understanding (1690), Locke rejected the notion of innate ideas and instead argued that everyone begins with a tabula rasa, or blank slate, and is shaped by his or her environment. This was a concept with radically equalizing implications. Locke therefore rejected Thomas Hobbes's theory that kings rule by divine right; how could they, if everyone was born equal? Locke also diverged from Hobbes in that he believed that the original state of nature was characterized by reason, equality and independence, rather than chaos, avarice, and savagery. People voluntarily left nature to enter into a society for the sake of mutual protection. Still, in any society, Locke contended, people are endowed with certain natural rights (to "life, liberty, and property"). In his enormously renowned political theory, Locke presented the idea of governmental checks and balances, which became a foundation for the U.S. Constitution. He also argued that revolution in some circumstances is not only a right but an obligation, which also clearly influenced the Founding Fathers. He most eloquently expounded his arguments concerning the natural rights of man in his 1680 work, Second Treatise on Government (or Two Treatises on Government), a book that Thomas Jefferson read at least three times.