Since its Parmenidean organization, ontology has built the portico of its ruined temple out of the following experience: what presents itself is essentially multiple; what presents itself is essentially one. The reciprocity of the one and being is certainly the inaugural axiom of philosophy - Leibniz formulation is excellent; 'What is not a being is not a being' - yet it is also its impasse; an impasse in which the revolving doors of Plato's Parmenides introduce us to the singular joy of never seeing the moment of conclusion arrive. For if being is one, then one must posit that what is not one, the multiple, is not . But this is unacceptable for thought because what is presented is multiple and one cannot see how there could be an access to being outside all presentation. If presentation is not, does it still make sense to designate what presents (itself) as being? On the other hand, if presentation is, then the multiple necessarily is.