Influenced by mercantilism and physiocracy theories, it took place from the late XVIII century to the late XIX century. It is considered that its main authors were Adam Smith, David Ricardo and John Stuart Mill, and the fourth, the unorthodox Robert Malthus, however, there is some evidence of previous contributions provided by French physiocrats and Spanish scholastics. They wrote especially about the theory of value, distribution theory and international trade.
The majority of the principles of the classical school of economics were set by Adam Smith in his work “An Inquiry into the Nature and Causes of the Wealth of Nations”, written in 1776. Smith defended free trade and free competition as the best way to make an economy grow, opposing his ideas to government intervention and the mercantilist theory that prevailed at that time.
David Ricardo developed the idea that every nation should specialize in the production of those goods in which they get an advantage towards other nations and produce it more efficiently. As for other commodities, instead of trying to be produced nationally, they should be imported.
Karl Marx studied the same matters, although with different conclusions and defending the working class, which makes him a classical economist in the eyes of some historians.
Thanks to these authors, the study of economics became more of a science, instead of just being some kind of philosophy.
Léon Walras, a French economist (1834-1910), is considered, along with 
Carl Menger, was an Austrian economist (1840-1921), who is considered to be, along with