Walter Burkert On Madness, Guilt And Sickness

Wikipedia: 

Walter Burkert was a German scholar of Greek mythology and cult. A professor of classics at the University of Zurich, Switzerland, he taught in the UK and the US. He has influenced generations of students of religion since the 1960s, combining in the modern way the findings of archaeology and epigraphy with the work of poets, historians, and philosophers.

An excerpt from, "The Orientalizing Revolution: Near Eastern Influence on Greek Culture in the Early Archaic Age" By Walter Burkert. Harvard University Press. 1998. Pg. 57-59.

"That social and physio-psychic ills were not clearly differentiated in archaic societies, that administration of justice and healing can be seen to fuse, has often been brought out and discussed in more recent anthropology. An offense is the source of illness, illness is the result of an offense, be it in the personal, the social, or the religious sphere. Even in Greek the word nosos, illness, embraces both, the physical and the social disturbances, ailments and sufferings. The effect of the therapy which the "knowing" specialist is able to apply is no less broad. In other words, the purification of Orestes could equally well be understood as the healing of an illness, even before Euripides brought this interpretation onstage in his tragedy Orestes. Orestes was both mad and guilty and had to be cured at both levels.
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If one regards Orestes as a case of sickness (nosos), then sickness appears personified to a remarkable degree: It is described as an attack by demons. The Erinyes are imagined as beasts of prey, "dogs" who want to suck his blood, leech the life-force from him. Remarkably enough, already in Homer sickness is once described as an "attack by a hateful demon." The magicians ridiculed by the author of the Hippocratic treatise On the Sacred Disease also speak of attacks (ephodoi) of demons or gods. The concept of savage, rapacious, carnivorous demons who cause sickness is common if not fundamental in Mesopotamian healing magic. But there is also the less personalized concept of the curse of murder, which has to be eliminated by a ritual in the "wash house."