Money is advanced purely with the intention of getting an increased sum back, without dirtying one’s hands with production or sales along the way.
Now, in M–C–M′, which, for Marx, is the paradigm of cap- italist production, the capitalist makes a profit. Marx’s ques- tion is this: how is it possible if everything exchanges at its value? That is, we know how to make a profit, if we are lucky, in a market of changing prices. But if prices remain constant, where does profit come from? How does it even get into the equation? We must, I think, confess that this is a puzzle.