What are some of the methods that were used to treat individuals who were presumably suffering from some form of mental illness before the Renaissance period? What was the rationale behind these methods?
Well, the Renaissance was preceded by the Dark Ages. Even though I think that the term “Dark Ages” carries with it a hint of presentism. I mean, the only reason that we see the Dark Ages as dark is because of the light of the Renaissance. At any rate, before the Renaissance mental illness was viewed as a wholly spiritual affair. Because the religion of Christian was firmly established in the Roman Empire by the 3rd century and Islam in greater Arabia by the 6th century an aura of mysticism enveloped most of the known world for some time. That is not to say that knowledge was not acquired during this time, but to say that knowledge was not usually acquired outside the context of religion. What logically followed from these two religious world-views was a belief in demons, evil spirits, and the like. In that context, mental illness was a religious matter rather than a medical matter. Most of the treatments required exorcisms, bloodletting, or simply isolation. I can imagine that some of these treatments worked from time to time because of the placebo effect. I mean if the person thought that a demon had been cast out of them, then they might find some relief through the action of the parasympathetic nervous.
Goodwin, C. J. (2005). A history of modern psychology (2 nd ed.). Hoboken, NJ: Wiley.