Surplus and Conditions of Existence.

The following is just a short piece that I posted in response to a common oversight by students in my current Marxian econ course. 
I figured I would share it with all of you as well.

The surplus value in the equation C+V+S=W
is necessary for capitalist growth and expansion, as many of you have written.
I want to add that there are many other conditions of existence of our modern capitalist society that are also fulfilled out of the surplus. 
Many (in fact a majority of) workers in a modern society are not productive (of surplus value).  Managers, service industry people, merchants, bankers, even myself, do not produce surplus, as we are not creating commodities (although the case could be made for education as a commodity). 
All of the value in society has to come from productive activity (by definition) and the rest of us who fulfill necessary conditions for the reproduction (and growth) of the system live off the surplus of the productive workers. To paraphrase the old man in dramatic fashion; we are the vampires of capitalism.