In this chapter, I complete my reconstruction of Freud's positive argument for the existence of unconscious mental states by providing a step-by-step account of Freud's philosophical argument that the mental-relevant essence of consciousness is brain representationality. I consider Freud's understanding of the mind–body problem in historical context, drawing on figures such as Fechner, Hughlings Jackson, and Titchener; Freud's perceptual model of consciousness and how it differs from Brentano's "inner perception" model; Freud's strategy of turning traditional psychophysical parallelism on its head to separate consciousness from the mental; and Freud's prescient hypothesis that brain representationality—representationality realized unconsciously in the brain—is the essence of the mental.