The term ‘Fundamental Symptoms’ enters the depth-psychological and psychiatric corpus primarily through Eugen Bleuler’s foundational 1911 monograph, where it serves as a technical distinction of the first order: the fundamental symptoms of schizophrenia are those intrinsic to the disease process itself — associative loosening, affective disturbance, ambivalence, and autism — as opposed to the ‘accessory symptoms’ (hallucinations, delusions, catatonic phenomena) that are psychogenically elaborated upon the primary deficit. Bleuler’s architecture is consequential because it inverts the diagnostic priority of his era: the florid accessories that previously defined insanity are demoted, while the quieter, pervasive disturbances of thought and affect are elevated as the true diagnostic core. This distinction carries immediate clinical and theoretical weight — fundamental symptoms may be present and severe without triggering hospitalization; it is the accessory phenomena that typically bring the patient to institutional attention. The tension Bleuler establishes between a primary, organically conditioned substrate and a secondary, psychically elaborated symptomatic superstructure anticipates later debates about primary versus secondary process, about the relationship between structural cerebral alteration and psychological elaboration, and about where psychiatry should fix its diagnostic gaze. Later depth-psychological authors engage the concept obliquely, invoking symptom hierarchies and the question of whether surface presentations or underlying functional disturbances constitute the ‘real’ pathology.