I'm currently reading Anne Harrington's The Cure Within: A History of Mind-Body Medicine (Norton, 2008). It's a history of how notions of positive mental health and the search for cures feed into today's conventional physical treatments. Why is there is such a violent battle between the alternative medicine camp and the traditional medical folks? I think this book assists in clarifying that issue.
One of the things Dr. Harrington does is illuminate the beginnings of skeptical thought about the origins of disease. She tells an interesting story about a young French woman whom relatives and the Catholic Church thought might be possessed by demons. The French King, Henry IV, whom as it happened had been raised as a Protestant (he was the one who decided Paris was worth a Mass), sent physicians to check things out. They sprinkled holy water on her but told her it was plain old water. No reaction, although there should have been, since demons don't like holy water. Then they read her passages in Latin from the Aeneid but told her they were passages from the Bible. Oh, dear--reactions aplenty. Conclusion--maybe the root of the young woman's problems (assuming she had any) was something other than demons. Good reading.