In this chapter, the essentialist and dualist approach of the self is explained. Essence ontology is discussed on the basis of Aristotle’s notion of ousia. Then it is demonstrated how Descartes adopts the features of Aristotle’s notion of “essence” but attributes them, first of all, to the self, and how he also highlights “independence” as the most important feature of “essence”, which has far-reaching implications for how the self is captured in Western thought. After having recaptured the most important features of the essentialist and dualist self and pointed out why it is so alluring, this chapter shows why this view cannot be sustained and indicates what is needed to develop an alternative, interactionist approach.