The analysis of Freud's argument for unconscious mental states reveals Freud to be both a materialist and a representationalist about the mental who postulates a theoretical entity of brain representationality as the essence of the mental and is a quasi-mysterian about consciousness. I consider in this chapter the remarkable prescience of Freud's position. The problems posed by Freud's argument have absorbed many of the leading philosophers of mind during the last half of the twentieth century and into the twenty-first, and there is no consensus resolution in sight. Moreover, several leading philosophers of mind express overall positions that are remarkably similar to Freud's. It seems fair to say that it has been a Freudian century in philosophy of mind.