Ricardo, Say and the liberal answer to Sismondi and Malthus
The French economist J.B. Say, who lived between 1767 and 1832, is famous for his “law of markets,” which allegedly proved that a general overproduction of commodities was impossible. Some authorities credit James Mill, the father of John Stuart Mill and a friend of Ricardo, for discovering this so-called law. The law, however, is generally known as “Say’s Law.” So that’s how I will refer to it here.
How did Say “prove” the impossibility of a general overproduction of commodities? He argued that while money makes the exchanges of commodities much easier, it is by no means absolutely necessary for commodity exchange. Commodity exchange can proceed, at least in principle, without money.
Therefore, Say abstracted away money. If money is left out, commodity exchange is the exchange of one commodity for another. The totality of these commodity exchanges makes up the market. Thus, the means of purchasing commodities are commodities themselves.
A Critique of Crisis Theory 