In response to Eric Schliesser etc.: The history of the subject matters not  
only in Astronomy but also in Philosophy. And I think what has been said in  
some philosophical context in this regard (see below) is also of relevance  
for the subject of the history of economic thought. As philosophical  
developments in the passage quoted below are likened to "blossom" and  
"fruit" which _both_ must be kept in mind if you want to  understand the  
concept of "plant", so there are several aspects of economics which are not  
just obsolete because they are antecedent. Thus, accounting might appear to  
be an old Italian hat (some would even say a Babylonian one). But in fact if  
you get your accounting wrong, you also are prone to get important aspects  
of economics wrong. -- I think in this thread there was some derogatory  
comment about "hydraulic macroeconomics" which was claimed to be surely dead  
and outlived. But you can only make a consistent statement in a  
macroeconomic context when you _do_ get your macroeconomic hydraulic  
accounting right. As soon as you wanted to argue that your "hydraulics" is  
right, you are back at the supposedly defunct economic thought. History of  
economic thought might help us to avoid re-inventing the consistency checks  
which have been invented before. Progressive is not the thought which  
forgets about the past. Progressive is the thought which embraces the full  
knowledge of the past. A good history of economic thought should be the  
vehicle for demonstrating this.  
  
G.W.F. Hegel, _Phenomenology of the Spirit_, Preface, see:  
http://www.class.uidaho.edu/mickelsen/texts/Hegel%20Phen/hegel_phen_preface.htm  
  
>The more the ordinary mind takes the opposition  
>between true and false to be fixed, the more is  
>it accustomed to expect either agreement or  
>contradiction with a given philosophical system,  
>and only to see reason for the one or the other  
>in any explanatory statement concerning such a  
>system. It does not conceive the diversity of  
>philosophical systems as the progressive  
>evolution of truth; rather, it sees only  
>contradiction in that variety. The bud  
>disappears when the blossom breaks through, and  
>we might say that the former is refuted by the  
>latter; in the same way when the fruit comes,  
>the blossom may be explained to be a false form  
>of the plant's existence, for the fruit appears  
>as its true nature in place of the blossom.  
>These stages are not merely differentiated; they  
>supplant one another as being incompatible with  
>one another. But the ceaseless activity of their  
>own inherent nature makes them at the same time  
>moments of an organic unity, where they not  
>merely do not contradict one another, but where  
>one is as necessary as the other; and this equal  
>necessity of all moments constitutes alone and  
>thereby the life of the whole. ....  
  
  
Gerhard Michael Ambrosi