פירוש על קידושין 56:2

The Talmud now goes back and asks how we would interpret the mishnah if we thought that coin could become an object of barter. To do this the Talmud basically rewrites the mishnah. The first part of the mishnah refers to coin, which can be used as barter, and the second half refers to produce (or what we could call edible products) which can also be used for barter. Note that prior to this we would not have thought that produce can be used for barter. If I want to trade you my Hershey bars for you Reeses cups, you would not take possession of the Hershey bars until you took them into your possession. But if it can be used as barter, then you would possess them as soon as I took the peanut butter cups.