Spinoza’s doctrine of essence (essentia) remains one of the most fraught issues among commentators. The most persistent controversy concerns whether Spinoza’s theory of essences is Platonist or not. Those who understand Spinoza as a kind of Platonist claim that essences in Spinoza have a non-actual existence – sometimes understood modally as a “possible” existence – distinct from the actual or real existence of the things of which they are the essences. To that effect, they point to various occurrences throughout the Ethics of the notions “formal essence” (E2p8, E2p40s2) and “actual essence” (E3p7, E4p4d), arguing on that basis that Spinoza operates with a distinction between essences of things that actually exist and essences of things that exist only formally. Giving the Platonist screw an additional turn, some commentators moreover argue that Spinoza is a kind of realist who allows for “species essences” or essences not only of singular things, but also of species or classes of things.