 Clearly, if the identity of indiscernibles is understood – as Leibniz intended – to assert that any two individuals must differ in some qualitative or relational way, B’s counterexample seems sufficient to refute it. But it seems that there is an easy answer available to A. For A could assert that the two spheres differ in some property or constituent that is neither qualitative nor relational: they could differ by haecceity. This leaves intact a trivial reading of Leibniz (that if individual x is distinct from individual y, then there must be some property had by x and not by y, or vice versa), and thus an apparently true version of the principle secure. Haecceities may not be the only way to preserve the principle against B’s counterexample. But the solution gives some prima facie plausibility to the possibility of haecceities. After all, if haecceities are required at least in cases of exact replicas, then it seems hard to resist the conclusion that they are responsible for individuation, period.