An engraving of John Locke from 1786. John Locke (1632-1704) was an English philosopher who spent his early years lecturing at Oxford University, England. He later spent fifteen years in France, where he met most of the leading Continental scientists and thinkers. On his return, Locke published his Essay Concerning Human Understanding (1690). In this, he suggested that a person's mind was a tabula rasa (blank slate) at birth. On this slate, knowledge was imprinted by experience. The essay also argued that the proper basis of knowledge was experiment. In the same year he published his Two Treaties on Civil Government in which he attacked the divine right of kings and the nature of the state.