Marx returns to his main thread: money and its circulation.

Circulation (in other words, “the turnover of money”) corresponds to “an opposite circulation, or turnover, of commodities. Money goes one way, commodities the other: “[a] commodity possessed by A passes into the hands of B, while B’s money passes into the hands of A, etc.”

More (pdf, 269 KB): The Chapter on Money Part 6: Money and its Circulation (pp. 186-203)