Physiocracy (from the Greek for "government of nature") is an economic theory developed by a group of 18th century Enlightenment French economists who believed that the wealth of nations was derived solely from the value of "land agriculture" or "land development" and that agricultural products should be highly priced. 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 François Quesnay (1694–1774) and Anne-Robert-Jacques Turgot (1727–1781). It immediately preceded the first modern school, classical economics, which began with the publication of Adam Smith's The Wealth of Nations in 1776.
The most significant contribution of the physiocrats was their emphasis on productive work as the source of national wealth. This is in contrast to earlier schools, in particular mercantilism, which often focused on the ruler's wealth, accumulation of gold, or the balance of trade. Whereas, the mercantilist school of economics said that value in the products of society was created at the point of sale, by the seller exchanging his products for more money than the products had "previously" been worth, the physiocratic school of economics was the first to see labor as the sole source of value. However, for the physiocrats, only agricultural labor created this value in the products of society. All "industrial" and non-agricultural labor was "unproductive appendages" to agricultural labor.
At the time the physiocrats were formulating their ideas, economies were almost entirely agrarian. That is presumably why the theory considered only agricultural labor to be valuable. Physiocrats viewed the production of goods and services as consumption of the agricultural surplus, since the main source of power was from human or animal muscle and all energy was derived from the surplus from agricultural production. Profit in capitalist production was really only the "rent" obtained by the owner of the land on which the agricultural production was taking place.