Anhedonia — the diminished or absent capacity to experience pleasure — occupies a significant, if unevenly theorized, position across the depth-psychology and allied clinical corpus represented in this library. William James introduced the term explicitly into the psychological-religious literature, deploying it to characterize Tolstoy’s confessional crisis as a ‘passive loss of appetite for all life’s values,’ a formulation that grounds the concept in existential and phenomenological soil before neuroscience claimed it. The addiction literature, particularly Flores drawing on Krystal, treats anhedonia as a core deficit in alcoholic and addicted populations — a consequence of infantile traumatization that forecloses ordinary gratification and drives compulsive substance use as the sole remaining vector of relief. Khantzian’s self-medication hypothesis intersects here, linking anhedonia-associated negative symptoms (affect flattening, avolition, asociality) to the selective pharmacological appeal of specific drug classes. Lench’s functional-emotions framework repositions anhedonia as an evolutionarily intelligible response: alongside anergia, it serves immune-system economy by suppressing incentive motivation during inflammatory states, mediated by pro-inflammatory cytokines acting on striatal circuits. This immunological reading stands in productive tension with the trauma-developmental account. Berridge’s incentive-sensitization work, meanwhile, targets the anhedonia hypothesis of dopamine directly, arguing that dopamine governs wanting rather than liking, thereby challenging the assumption that dopamine suppression simply produces anhedonia. Across these positions the term functions as a hinge between psychodynamic, neurobiological, and phenomenological vocabularies.