I appreciated Paul Cockshott's helpful comments in ope-l 5139. It is indeed
important to keep in mind that the equality of the output prices of "period n"
and the input prices of "period n+1" requires some very restrictive
assumptions in order to be considered necessary. As Paul mentions, two of
those assumptions are that wholesale and retail prices do not diverge, and
that production periods are of fixed length and synchronized throughout the
economy. Another restriction is that circulation time is zero.
In the general case, I interpret Marx to say that the necessary outlay on
means of production, which determines the value transferred from constant
capital, is itself determined by the price of the means of production at the
moment when their own use-value is destroyed.
Andrew Kliman