Background. This paper is based on a rich archive of 1151 letters by patients, who were admitted to the Royal Edinburgh Asylum during the reign of Thomas Clouston (1873–1908).

Methods. All letters were examined for evidence of psychopathology, and the material obtained was organized under the various psychopathological categories, such as delusions or hallucinations, as defined by Sims (1988).

Results. A descriptive account of patient symptomatology is given. It is found that nineteenth century psychopathology is very similar to that of the modern day, and that most forms of morbid mental phenomena can be found in the patients' letters. More specifically, most of the cardinal symptoms of schizophrenia were described in the patients' correspondence. The letters also illustrate how mental symptoms reflect the cultural and scientific concerns of their time.

Conclusions. The evidence in the patients' letters argues for the unchanging nature of mental illness across time, at least for the last 120 years. It also demonstrates that patients admitted to the Royal Edinburgh Asylum suffered from serious mental illness, and it undermines the view that the Asylum was simply a dumping ground for society's disaffected.