This is a second post grabbing some insights from a fascinating book by Darrel W. Amundsen—Medicine, Society, and Faith in the Ancient and Medieval Worlds (Baltimore, MD: Johns Hopkins University Press, 1996). The first post shared some of Amundsen’s observations on early Christian attitudes toward medicine and physicians.
In the excerpts in this post, Amundsen explores what medieval Christians thought caused illnesses, starting with some remarks on causality in mental illness or insanity. Along the way, he busts some myths. For example, many modern commentators believe–based on some misleading evidence in the sources themselves–that medievals assumed all illnesses came from devilish or demonic sources, or, a variant, from some hidden sin in the sick person. Not so, says Amundsen.
Rather, first, they saw all illnesses as coming ultimately from God. But second, they perceived and affirmed many levels of causality, and they were comfortable shifting back and forth between these levels depending on the audience and occasion of their writings.
And third, although sin was in a general sense considered the source of illness (as of all dysfunction in our world), a person’s particular sins or general sinfulness are rarely mentioned in medieval sources as the cause of their illness.
Here’s Amundsen on the subject:
“The penitential [manual]s addressed the issue of causality [in cases of insanity] only when insanity led to suicide. The Penitential of Theodore (668 – 90) specified that ‘if a man is vexed by the devil . . . and slays himself, there may be some reason to pray for him if he was formerly religious.’ Other reasons for insanity leading to suicide were then given: despair, fear, unknown reasons, or a sudden seizure. . . . Because it is so common to assume that in the early Middle Ages demonic causality was accepted for most disease, and certainly for mental illness, such natural causes as despair, fear, sudden seizure, and ‘unknown reasons’ may surprise us. Such explanations, however, occur with some frequency. . . .  [I]n 1023, Fulbert of Chartres, when comparing the functions of priests and physicians, said that ‘it is a physician’s duty to offer those who are suffering from depression, insanity, or any other illness what he has learned in the exercise of his art.’ Jerome Kroll is undoubtedly right when he says of this period that ‘mental and spiritual illnesses were attributed as much to overwork, overeating, and overindulgence in sexual activity as to climatic conditions, magic spells, and demonic possession.’ There is, however, considerable ambiguity in the literature. There is, however, considerable ambiguity in the literature. This ambiguity arises from two different sources. First, there was much imprecision in identifying the causes of mental illness. The second source of ambiguity is the failure of the modern reader to enter sufficiently into the early medieval structure of reality, in which ultimate and proximate causality may be spoken of in the same breath without any distinction being made, and an intermediate (usually demonic) causality mingled in with the former two. Any one of the three may be mentioned as the cause of a particular condition, and taken by the modern reader as the author’s perceived sole cause, whereas the choice of that cause was simply determined by the author’s desire to emphasize one, with no intention of making it appear exclusive. This applies not only to considerations of madness but also, indeed even more so, to sickness generally.” (186 – 7)
“A degree of demonic causality was seen in many conditions, and some people may have attributed nearly every adverse condition to demons. But the sources adequately demonstrate that on the whole God was viewed as the ultimate dispenser of human suffering, including sickness. As a general rule, when early medieval sources mentioned direct demonic involvement, which they frequently did, the condition was clearly regarded as possession, whether accompanied by sickness or not. They delighted in relating stories of exorcisms, but they were equally eager to tell of healings through relics, healings from which exorcism is absent. Furthermore, the most holy of the saints could not conceivably have been possessed by demons, but yet were frequently ill; some indeed seemed to gain a high degree of sanctity through their sicknesses.” (187)
“Another commonplace encountered in modern assessments of the early Middle Ages is the assertion that early medieval people saw sin as the cause of most sickness. Here there is room for much confusion because the relationship of sin with sickness can appear at three different levels. First, sin was certainly regarded by early medieval authors as the cause of sickness in the sense that without sin there would have been no  material evil. This, although not expressed, was an underlying assumption of the sources. Second, one’s own general sinfulness was often given as the cause of one’s own sicknesses. Third, sickness, it was thought, might result from specific sin. This last statement is very seldom encountered except in denunciations of and warnings to entire communities, and then the emphasis was often on general moral laxity, which makes it nearly indistinguishable from the second category. We should also note that it is one thing to maintain that a person is sick as a punishment for a specific sin to which he or she is obstinately and tenaciously clinging, but it is quite another matter to attribute one’s own sickness to one’s general sinfulness and see the sickness as part of God’s punitive and refining process.” [187 – 8]