The author investigates conversion, the process by which psychic contents are transformed into bodily symptoms. The author concludes that this process cannot be explained by libido theory or by assuming the existence of a psychic energy. He argues that although Freud was convinced that “the leap from a mental process to a somatic innervation … can never be fully comprehensible to us,” this process is, nonetheless, comprehensible in terms of Freud's own conceptualisation. To understand this process, one must take the characteristics of the primary process to which the “replacement of external by psychical reality” belongs as radical as his thesis of a hallucinatory wish fulfilment. This thesis includes not only the hallucinatory satisfaction of instinctual wishes, but also the hallucinatory satisfaction of the desire to avoid unpleasure, which is understood as a process by which the internal conditions of this affect are displaced from the presentational world into perceptions via conversion.