 Several of Kripke’s exemplary cases concern theoretical identities; these are typically identities of the form C = T, expressed using a common name for a kind, ‘C’, and a technical identification of the kind, ‘T’, typically thereby telling us what that kind is. Examples: light is a stream of photons; water is H2O; lightning is an electrical discharge; gold is the element with atomic number 79. This might give the impression that Kripkean essentialism is just a matter of the necessity of identity. However, in several of his discussions Kripke does provide separate, independent arguments on the one hand for the (necessary) necessity of being T for being C and on the other hand for the (necessary) sufficiency of being T for being C. In general, where K is a kind and P is some property, arguments for □∀x(Kx→Px) can be decoupled from arguments for □∀x(Px→Kx).