Medieval ideas about mental illness were almost as bewildering an assortment as our own, but a unifying theme was supplied by the cognitive theory outlined here. It was generally believed that the normal waking person’s activities were under the control of the mind. In cases of insanity this control was disrupted or corrupted and behavior would then, like an animal’s, be simply determined by the inner senses and the appetites. Consequently, in later medieval legal theory and practice, and in the writings of theologians, the insane were not held accountable for their actions.
At least in the later Middle Ages, the normal causes of disruption were believed to be physiological or environmental. Probably the most influential medical account of mental illness stemmed from the humors theory originally proposed by Hippocrates, and widely elaborated by ancient and Islamic physicians. Mental disorder was thought to result from either an imbalance, or more usually an abnormality, in one of the four humors believed to be important in determining individual differences: blood, phlegm, yellow bile (choler), and black bile (melancholy). Typically, phrenitis (or frenzy) was held to result from overheated yellow bile, melancholy from abnormal black bile, and epilepsy from the blockage of the passages of the brain with abnormal bile or phlegm. Different symptoms might arise from different kinds of humoral abnormality or from the abnormality manifesting itself in different parts of the body. Thus, for example, in Constantinus Africanus’s account of melancholy, feelings of alienation might result from black bile affecting the heart, and fear of the future from fumes of black bile literally darkening the imagination. Unsurprisingly, the symptoms of melancholy in his account are quite diverse, easily extending to cover those of present-day schizophrenia and endogenous depression.
Another medical theory distinguished mental disorders by the ventricle affected. Mania affected the front, melancholy the middle, and lethargy the rear ventricle. This idea was not easily compatible with the humors theory, but did fit easily with medieval cognitive theory.
Both medical practitioners and laypeople recognized the role of environmental factors in precipitating mental disorder. Thus, for example, the medieval English Court of Chancery seems to have determined such causes of mental disorder as blows to the head and grief, Constantinus Africanus’s writings on mental disorder include a treatise on love-sickness. Interactions among the various different causes was also widely acknowledged. So, for example, people who were naturally of a melancholic humor were at particular risk if they undertook occupations likely to induce melancholy. Students and monks were believed to be especially susceptible.
Western European accounts from the early part of the Middle Ages often blamed mental disorder, especially where the symptoms resembled those of epilepsy, on demons, an attribution that has precedents in the New Testament. In the Islamic tradition and in the later Middle Ages in Christian Europe, mental disorder was less widely attributed to demonic possession, but the diagnosis was still occasionally made, especially in religious writing. The diagnosis seems to have been reserved mainly for unusual cases, for example, if a person actually claimed to be a demon. Toward the end of the Middle Ages, cases of demonic possession, among a variety of other ailments, sometimes spurred a hunt for the witch responsible. However, in these cases the object of the witch hunt was someone who might have brought about the possession, not the afflicted individual himself or herself.
The demonological and medical theories were not mutually exclusive. Religious writers describing cases they ascribed to possession sometimes reveal a fair knowledge of medieval medical theory. Moreover, it was often held that demons took advantage of an existing constitutional weakness, such as a tendency toward melancholy, in selecting their victims. Finally, possession too was believed to feature the disruption of the mind’s normal control over behavior and its usurpation by a demon.
Treatments for mental disorder were quite diverse. Some were theoretically based: bloodletting, baths, head surgery, or a diet change to rid oneself of noxious humors: sexual diversion to aid the lovesick: exorcism and Holy Communion to aid the possessed. Others were not: music, pleasant scenes, prayer, and religious relics were thought to be beneficial regardless of the diagnosis (which was often tentatively held in any case). Records of the illnesses of the painter Hugo van der Goes (c. 1435-.1482 CE) and the French King Charles VI (1368-1422 CE) portray well-meaning onlookers suggesting a variety of diagnoses and remedies, none of them very successful. An instance of the solicitude shown Charles during his periods of illness was his court’s procurement of a mistress, Odette de Champ-divers, when the king refused to recognize his wife.
Some medieval treatments must have been painful, and head surgery was probably dangerous. Moreover, the long-term mentally ill, especially those without substantial means, seem to have been low on priority lists for institutional care. However, neither painful treatment nor frequent neglect seems to have been motivated by a desire to punish either the patient or any demon thought to possess him or her. The idea that people possessed by a demon could be cured by torturing them or burning them at the stake would have seemed to a medieval clergyman quite as bizarre as it does to us.