Karl Marx. Capital Vol One Ch4

The general formula for capital

Marx compares two types exchanges. Money to buy a good to resell for more money (M -> C -> M) and a good to sell to buy another good (C -> M -> C).

To exchange a good for money to buy another good is based on the want of a specific thing that has definite physical attributes. When someone buys something in order to sell it at a higher price the goal is to increase an abstract value which ideally could be any number. The latter exchange is a capital exchange (exchanging money in order to receive more money).

Interest bearing capital seems to Marx to remove commodities from the calculation. Interest just boldly states that money is worth more money.

Marx also contrasts a miser to that of a capitalist. A miser saves money and withdraws money from circulation while a capitalist puts money into circulation.

But the important bit to consider is that a capitalist treats a money like a good and goods like money that is worth more than it was originally. Or at least the role money and goods play is put on their heads in a slightly perverse way.