 One way to attempt to precisify the notion of essence is to note that we are here concerned with identity in the sense of individuality rather than the relation of identity. In other words, identity-dependence expresses the determination of the individuality of objects in terms of the individuality of other objects. Thus, the identity-dependence of a set upon its members could be regarded as a consequence of the fact that the Axiom of Extensionality functions as the criterion of identity for sets. The set’s members determine the individuality of the set—they individuate the set. Notice, here, that we allow that x may be said to depend for its identity upon y even in cases in which the identity of y alone does not suffice to fix the identity of x. So, for example, a set with two or more members depends for its identity upon each of them, although its identity is only completely fixed by the identities of all of them.