At this point in Manuscript Marx undertakes a (rather rambling) examination of what “capital” actually is, basing himself in part on what capital is taken to be in the work of the political economists, and in part on what he has already himself developed in the Manuscript.

Marx begins by noting that capital is to be distinguished from money; or, more precisely, money that is capital is to be distinguished from money that is not. “Money as capital is an aspect of money which goes beyond its simple character as money,” Marx points out. But to posit money as capital is to posit capital as a form (money) which pre-exists it. We have already discussed money as money; what we need then to establish is, in the abstract, what capital is.

More (pdf, 89 KB): The Chapter on Capital Part 2: A Preliminary Discussion: What is Capital? (pp. 250-261)