 Thus is concretion secured, but whither simplicity? A concrete state of affairs such as Socrates’ being pale is a complex both the subject and the property constituent of which are necessary for its identity.  Property instance or tropes, by contrast, are simples: the paleness trope in Socrates, though it cannot ‘migrate’ to Plato, does not have Socrates as a constituent and so is not tied to the philosopher for its identity. Now McCann is well aware that the ontological complexity of concrete states of affairs does not comport well with divine simplicity. But he thinks it is the best we can do.