The thing exists in a web of relations as does the idea of the thing, but the idea of a relation is not the same as the relation of ideas and so a continual slippage occurs between these intertwined webs. This gives rise to a cloud of eddies and parasites which, when the thing is real, can be periodically reduced or purged entirely. If the self is real then this ought to happen for it too, a succession of reality-checks that maintain the stability of its environment. But this is just what we don't observe, or at least we observe it failing as often as succeeding. The self is therefore an entity of the same kind of semi-virtuality as say, the State, or any other useful cultural abstraction, and subject to similar kinds of changes.