RE the points made by Alain & Jean:
 
Please read my my comments in their context, as a response to Pat Gunning, to raise a question about the suggestion that economics must by definition be concerned with the theory of S&D, comparative advantage etc etc. 
 
I realize that Cournot elaborated a S&D mechanism before 1850, but his work hardly dominated the economic discourse of his day. I was not slighting him because he wrote in French rather than English. Nor was I slighting Gossen or Rau because they wrote in German.  
 
I mentioned Say, by the way. As far as Say's Law is concerned: it implies only that the level of aggregate demand will be adequate to absorb whatever level of output the economy happens to produce. In itself it doesn't imply full employment, and I find no evidence that Ricardo drew any conclusions from it about the tendency of the labor market to clear: quite the contrary--his machinery chapter suggests that he understood that labor markets don't routinely clear. 
 
Gary Mongiovi