In this chapter, I begin my reconstruction of Freud's positive argument for the existence of unconscious mental states. Freud attempts to show that the essence of the mental is brain representationality, not consciousness. A requirement for mounting such an essentialist argument is to identify the mental-relevant essence of consciousness. Based partly on a review of the literature, I argue that the mental-relevant essence of consciousness is whatever enables consciousness to play the role it (apparently) does in the capacity for rationality. The first part of Freud's overall argument, then, is to show that it is the representational content of phenomenal consciousness that provides the apparent ability of consciousness to provide rational capacities.