It was an empirical discovery that Phosphorus is Hesperus. According to
Kripke, this was also the discovery of a necessary fact. Now, given Kripke’s theory of
direct reference one could wonder what kind of discovery this is. For we already knew
Phosphorus/Hesperus, and we also knew that any entity is, necessarily, identical to itself.
So what is it that was discovered? I want to show that there is more to this widely known
case than what usual readings, and critics, reveal; and I want to show this under the
Kripkean pattern that what was discovered is the plain fact of identity that Phosphorus is,
and necessarily is, Hesperus. Moreover, I will show how both Kripkean theses, the necessity
of identity and the direct theory of reference, should not be kept apart to understand the
kind of discovery this is. In particular, understanding the kind of discovery we made will
help us see how intuition is displayed in metaphysics, and how metaphysical impossibilities,
and metaphysical modality in general, can be discerned by reason and separated from other
modalities. The study of this discovery will help us see, in a line, how identity belongs to
the inner and most profound structure of reality and to the most profound structure of
cognition and language.