An obstacle to understanding Freud's philosophical contribution is that he is primarily known as a clinician and clinical theoretician who put forward theories of repression and the dynamic unconscious to explain the symptoms of psychopathology. Many of his admirers prize that strictly clinical image of Freud. However, as I document in this chapter, Freud clearly indicated throughout his work that at the foundation of his clinical contribution was a more basic philosophical thesis that mental states can be unconscious. In this chapter, I disentangle Freud's clinical theorizing about the dynamic unconscious from his philosophical argument about the descriptive unconscious to set the stage for the analysis to come.