Physiocracy 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. Physiocracy 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.