A key problem for trauma theory is bringing internal and external sources of distress together, paying sufficient attention to each. While Wilfred Bion is well-known among psychoanalytically-oriented trauma theorists, the relevance of his work to trauma is not always fully appreciated. Bion focuses on the inability to know. Freud made Eros and death the driving forces of the psyche, particularly in his later work; Klein made love, hate, and reparation central; Bion makes knowledge central. In conclusion, I turn to Stephen Mitchell in order to explain how focusing on the inability to know helps us better understand trauma.