Physicalism, the currently dominant philosophy of mind, is the thesis that everything is physical.¹ To clarify what this means, I argue that physicalism is a thesis about actually exemplified individual essences. According to physicalism, the only class of actually exemplified individual essences is characterised like this: no actually exemplified individual essence essentially entails properties that conceptually entail the existence of a subject of experience. I spell out the truth-conditions of physicalism before turning, in the next chapter, to a refutation of physicalism.