My response to Alex is this:

yes of course, commodity production is not unique to capitalism; it exists in germ in ancient society, and in fact even in tribal society; but reaches its fullest development, "finds itself", only in capitalism, when the commodity relation penetrates every aspect of human existence.

Surplus Value, is characteristic of "civilisation", i.e. class society up till now. Thus, capitalism is only one specific mode of production of surplus value, as against feudalism, slave society, etc., viz., one in which labour power becomes a commodity and accumulated surplus value takes the form of capital..

In general, the task of identifying the essence and notion of a thing is NOT finding what is unique to it. For example, when we say that "human is a tool-making animal", most humans don't make tools and other animals do, but it's still true. "Common uniquely identifying characteristic = concept" is the so-called abstract universal" of set-theory. The turht of a thing is in its genesis.

thanks Alex!

Andy