We now turn briefly to the possible objection that our Border Dissolves would not work in real life in the way we have supposed because, in actuality, personal identity resides in some sort of metaphysical substance. Someone who subscribed to such a view could claim that the BST or teletransporter examples, for instance, would not really preserve personal identity because such devices would not make copies of, let us say, for instance, one's "immaterial soul."