Sir William Petty (26 May 1623 – 16 December 1687) was an English economist, physician, scientist and philosopher. He first became prominent serving Oliver Cromwell and the Commonwealth in Ireland. He developed efficient methods to survey the land that was to be confiscated and given to Cromwell's soldiers. He also remained a significant figure under King Charles II and King James II, as did many others who had served Cromwell. Petty was also a scientist, inventor, and merchant, a charter member of the Royal Society, and briefly a member of the Parliament of England. However, he is best remembered for his theories on economics and his methods of political arithmetic. He is attributed with originating the laissez-faire economic philosophy. He was knighted in 1661. Source: Wikipedia (en)