Manifesto of the Communist Party (1848), Karl Marx & Friedrich Engels
Value, Price and Profit (1865), Karl Marx
Wage-labour and Capital (1847-1849), Karl Marx
When told what has been occupying me for several hours today, several people reacted with surprise: “You mean you haven’t read that before!?” (Parenthetically, it turned out on each of these occasions that the disappointees had themselves, in point of fact, never read the Manifesto or the other works either.) So now I have. The comments below are highly simplistic, and I am almost embarrassed to reveal them here.
(1) As is well known, one major ‘materialist’ assertion of classical Marxist thought is that modes of production ground the intellectual and political structure – and hence history – of societies. Unsurprisingly, this issue has inspired a lot of subsequent work. (2) A second is the labour theory of value. I hope to write much more on both of these at some point.
(3) One thing that really stands out in these foundational works is their outspoken confidence in the inherent moribundity of capitalism. Marx and Engels recognized, and even discussed in considerable detail, the internal strife within both the proletariat and the bourgeoisie. So what made them so convinced that the proletariat, as a unit, would – as it were – destabilize history? Is it possible that in their whole-hearted embrace of this proleteriat|bourgeois categorization, M&F quite naturally came to foresee (presumptuously) a competition between them, rather than a stabilizing dynamic hierarchy within each of them?
(4) Marx did in fact perceive the actual self-limiting force inherent in capitalism(*), but did not recognize it as such. Ironically (and when one ponders this, the force of the irony truly doubles one over!), this moribundity is materialistic rather than social in nature! To wit: capitalism’s(*) requirement for groWTH, which accounts for its expansive buoyancy, ensures the presence of an insurmountable iron wall.  (If more economists were physicists it wouldn’t have taken their fringe thinkers until 1972 to realize this. Conversely, if more physicists were economists we probably wouldn’t have cell-phones.) Anyway, Marx fully understood that capitalism(*) and growth are inseparable. (This inseparability has been canvased more recently and colourfully by William Greider.)
(5) Marx held that under unregulated capitalism(*), wages converge towards bare sustenance levels.
(6) Marx held that unregulated capitalism(*) leads to agglomeration and monopolization.
(*) I should be taken as employing the term ‘capitalism’ so grudgingly as to barely be employing it at all.