(I should say I'm a :LIB: and am reading the abridged Julian Borchardt version of Capital, so maybe there's an excised chapter that explains this or maybe there's a later chapter that does - I'm currently reading Decade of the Rate of Profit from Part II, chapters 13-15)

It seems that he insists surplus value is directly related to variable capital (i.e. labour), but other than semantically defining it that way, is this necessarily so? From the capitalist perspective how is labour really any different from any other input?

For instance, if one has a theoretical FALSC-style factory with no labour, surely one could still add surplus value to goods?