The physiocrats were a group of economists who believe that the wealth of nations was derived solely from the value of land agriculture or land development. Their use of the term laissez faire meant that the only legitimate form of government revenue derived from the value of land. Their theories originated in France and were most popular during the second half of the 18th century. Physiocracy is perhaps the first well developed theory of economics. The movement was particularly dominated by Anne-Robert-Jacques Turgot (1727–1781) and François Quesnay (1694–1774). It immediately preceded the first modern school, classical economics, which began with the publication of Adam Smith's The Wealth of Nations in 1776.