In his response to Pat Gunning, Gary Mongiovi wrote: "The theory of 
demand & supply is a post-1850 development ..."  Gary thus excludes 
Smith, Ricardo, Malthus, and Mill from developers of the supply and 
demand theory of exchange  values or price.  I read Smith's Book 1, 
chapter 7 as the culmination of his explanation of market price 
determination begun from chapter 5 of the same book.  Ricardo also 
affirms that "the 7th chap. of [Smith's] Wealth of Nations" is where 
"all that concerns this question [of value or price determination] is 
most ably treated" (_Works_, 1: 91).  Malthus (1936, 62) argues that 
"the value of commodities in money or their prices are determined by the 
demand for them, compared with the supply of them.  And this law appears 
to be so general, that probably not a single instance of a change of 
price can be found, which may not be satisfactorily traced to some 
previous change in the state of the demand or supply."  Mill (_Works_, 
3: 467-68) also explains market price determination by supply and 
demand, applying a "mathematical analogy ... of an _equation_. ...If the 
demand increases, the value rises; if the demand diminishes, the value 
falls off falls: again, if the supply falls off, the value rises; and 
falls if supply is increased."

Pat Gunning's response to Gary, including arguing that "demand and 
supply reflect a shift from a classical to a neoclassical approach the 
the subject matter ..." appears to acquiesce with Gary's claim.  So, I'd 
like to ask, In what sense was the theory of demand and supply as an 
explanation of market price determination a post-1850 development?

James Ahiakpor