Karl Marx's Capital: Chapter 14: Counteracting Influences
Read this chapter, in which Marx shows the effects of his law that within a capitalist economic structure, the tendency of the rate of profit must fall. This leads to increasing intensity of exploitation as well as other effects that contribute to the downfall of capitalism.
Click https://web.archive.org/web/20140516080054/http://www.marxists.org/archive/marx/works/1894-c3/ch14.htm link to open resource.