  On the other hand, the inventory of particulars is different in all three cases. For Leibniz, only spiritual monads exist, for Brentano, there are spiritual souls and material bodies, but for Kotarbiński, only material bodies occur in the world. Thus, we have one formal ontological thesis (RO) and its three different metaphysical concretisations. Using Kotarbiński’s terms, concretism points out an ontological feature of reism, but pansomatism concerns metaphysical matters. If this is accepted, reism in the sense of (RO) becomes a kind of nominalism. Due to its connection with LO, it is a fairly strong version of nominalism, probably stronger than any other. This is due to the fact that identity is defined in elementary Ontology, but is not definable in standard first-order logic.