Ricardo\u27s model of comparative cost: about physical masses moving in linked economic systems

The concept of comparative advantage, developed by D. Ricardo in 1817, has the important result that even when a nation does not have an absolute advantage in the production of particular goods or services with another nation, it can still be beneficial for that nation to engage in inter-national trade. - Unlike the traditional approach that uses labor cost and productivity to intro-duce Ricardo\u27s revolutionary concept, the present paper chooses the two products rice and wheat as example and focuses on physical mass of these cereals that is moved and traded between two nations. The study shows that obeying Ricardo\u27s concept triggers a maximum of mass flow inside the total system called "trading nations". This outcome might be helpful when issues like "sustainable development" and "sustainable economic growth" are discussed