Jean-Baptiste Colbert's work in 17th-century France came to exemplify classical mercantilism. In the English-speaking world, its ideas were criticized by Adam Smith with the publication of "The Wealth of Nations" in 1776 and later by David Ricardo with his explanation of comparative advantage. Mercantilism was rejected by Britain and France by the mid-19th century. The British Empire embraced free trade and used its power as the financial center of the world to promote the same. The Guyanese historian Walter Rodney describes mercantilism as the period of the worldwide development of European commerce, which began in the 15th century with the voyages of Portuguese and Spanish explorers to Africa, Asia, and the New World.