From your perspective, an object that belongs to you is: not yours, mine, not you, me and from my perspective it is: yours, not mine, you, not me. When the object becomes mine, all of these elements are inverted. When we have each exchanged an object we are offering for an object we want, the designations are inverted for each for both of us. During the steps in between, the counting of the objects gets mixed up, as if me is in part you and you is in part me. This mixing up of the counting of the objects controls the process of exchange. You and me are treated symmetrically throughout the process.