Money

Thus, back to x of A exchanges for y of B.

In the real world: x of A equals y of B, z of C, w of D and so on and so forth.

Reversing this reveals that A itself is money. Thus, money is just a sort of commodity but it functions differently from others because it can be easily used to express them. But it can do this only because it represents a certain value of abstract labor, just like any other commodity.

money becomes capital