Adam Smith (1723-1790) is often called the founding father of political economy. His main contribution to economics, a vision of the economy as the evolution of the division of labour, is very often belittled, although it is fundamental to understand his depiction of markets. He was a famous critic of the mercantilist policies of many nations.
An inquiry into the nature and causes of the wealth of nations, available from the Libertyfund Library of Economics & Liberty.