Always doubting identity, always concerned to construct it, shore it up etc. This plays on many different levels and is a fuel for the mind, although not a clean one. The only part of this that is avowable is the concern with metaphysical identity. What is avowable or not avowable is itself an issue about identity. The relations of subject to subject where both sides remain fully subjective is not in any way analogous to that of subjects to objects - which is essentially that of objects to objects. Subjects proper don't 'exist' - they are perhaps more like fields of coherent propensities. One such field can pervade another, knowingly or unknowingly.