Is a naturalistic account of reference possible? Here is a simple argument to the effect that it is not: Let R be the relation that allegedly naturalizes reference, and consider the predicate "being an object that does not stand in the relation R to this expression". Call this predicate "P". On the face of it, P is a counterexample to the alleged naturalization, since it appears to refer to all and only those objects that do not stand in the relation R to it. Actually, an argument like this was advanced more than twenty years ago by the late Paolo Casalegno. Although for various reasons it has not been given due attention by the philosophical community, the argument is interesting in its structure and remarkable in its conclusion. In this paper I shall reconstruct it in detail and discuss it. Then, I shall show that the argument fails, since, contrary to what Casalegno claimed, under certain conditions P is paradoxical, hence not a referring expression. My rejection builds on the fundamental distinction between simple and compound expressions, namely on the compositional structure of natural languages. If I am right, whether any attempt at naturalizing reference that takes care of this distinction will succeed remains an open empirical question.