Reil publishes essays that not only creates the umbrella of "psychiatry," which mental illnesses fall under, but it also advocated for asylums for the mentally ill, and a more ethical treatment of people who are suffering from a mental illness (Schochow & Steger). This essentially establishes the human mind as something to be studied scientfically, rather than existing in the abstract. 

Citation:

Schochow, Maximilian, and Florian Steger. “Johann Christian Reil (1759–1813): Pioneer of Psychiatry, City Physician, and Advocate of Public Medical Care.” American Journal of Psychiatry, vol. 171, no. 4, 1 Apr. 2014, pp. 403–403., https://doi.org/10.1176/appi.ajp.2013.13081151.