i've done some reading about the trials. there are various theories about why what happened in salem, mass back then happened. the most plausible to me is ergotism poisioning. from the article by linda caporael:
Ergotism, or long-term ergot poisoning, was once a common condition resulting from eating contaminated rye bred. In some epidemics it appears that females were more liable to the disease than males (19). Children and pregnant women are most likely to be affected by the condition, and individual susceptibility varies widely. It takes 2 years for ergot in powdered form to reach 50 percent deterioration, and the effects are cumulative (18, 20). There are two types of ergotism--gangrenous and convulsive. As the name implies, gangrenous ergotism is characterized by dry gangrene of the extremities followed by the falling away of the affected portions of the body. The condition occurred in epidemic proportions in the Middle Ages and was known by a number of names, including ignis sacer, the holy fire.
Convulsive ergotism is characterized by a number of symptoms. These include crawling sensations in the skin, tingling in the fingers, vertigo, tinnitus aurium, headaches, disturbances in sensation, hallucination, painful muscular contractions leading to epileptiform convulsions, vomiting, and diarrhea (16, 18, 21). The involuntary muscular fibers such as the myocardium and gastric and intestinal muscular coat are stimulated. There are mental disturbances such as mania, melancholia, psychosis, and delirium. All of these symptoms are alluded to in the Salem witchcraft records.
It is one thing to suggest convulsive ergot poisoning as an initiating factor in the witchcraft episode, and quite another to generate convincing evidence that it is more that a mere possibility. A jigsaw of details pertinent to growing conditions, the timing of events in Salem, and symptomology must fit together to create a reasonable case. From these details, a picture emerges of a community stricken with an unrecognized physiological disorder affecting their minds as well as their bodies.
1) Growing conditions. The common grass along the Atlantic Coast from Virginia to Newfoundland was and is wild rye, a host plant for ergot. Early colonists were dissatisfied with it as forage for their cattle and reported that it often made the cattle ill with unknown diseases (22). Presumably, then, ergot grew in the New World before the Puritans arrived. The potential source for infection was already present, regardless of the possibility that it was imported with the English rye.
Rye was the most reliable of the Old World grains (22) and by the 1640's ot was a well-established New England crop. Spring sowing was the rule; the bitter winters made fall sowing less successful. Seed time for the rye was April and the harvesting took place in August (23). However, the grain was stored in barns and often waited months before being threshed when the weather turned cold. The timing of Salem events fits this cycle. Threshing probably occurred shortly before Thanksgiving, the only holiday the Puritans observed. The children's symptoms appeared in December 1691. Late the next fall, 1692, the witchcraft crisis ended abruptly and there is no further mention of the girls or anyone else in Salem being afflicted (4, 9).
the article goes on to talk about the geography salem and how there were more affected in one part of salem than the other. it is all quite interesting.
i personally am not that thrilled with this movie. witchcraft and witches are still misunderstood in this country, in fact bush himself does not recognize the practice of wicca or paganism as real religions. people who identify as witches still have to hide in this country under which "freedom of religion" was one of the tenants that we were founded. it is all very disturbing.
btw, one site that i've found to be pretty good as far as the facts of the trials, as they were then, is: salem witch trials page