If we imagine anything that we should call a justification, some private regularity it must be something which, if we saw it, we should call a regularity. But what would in our case mean seeing his private regularity? We haven't given it any sense. That is, we have indeed given the expression to feel what he feels sense but with
particular criteria for the identity. If we now talk of identity & don't wish to use these criteria we are left without any unless we give fresh ones. And of course I know perfectly well that we are thinking of criteria similar to the ones of physical objects only we can't apply any such criteria in our case & that's what we mean by talking of the privacy of the objects. Privacy here really means the absence of means
of comparison. Only we mix up the state of affaires when we are prevented from comparing the objects with that of not having fixed a method of comparison. And in the moment we would fix such a way of comparing we would no longer talk of ‘sensations’.