Magic or medicine?

Writing “The Wisdom of Rhiannon” was a test of my beliefs. I was trained as a physicist which fashioned me to see the physical world in which we live in a certain way. So I was challenged in trying to determine what “powers” did the Druids have; any, or was it trickery, or a good knowledge of the natural world, for example, in predicting eclipses? What was the nature of ancient knowledge? Certainly there is evidence of quite remarkable medical knowledge, for example, trepanation, a delicate surgical technique for making a hole in someone’s skull, with evidence that the technique dates back as far as 6500 BC, with plenty of people recovering from the operation.
And this was my difficulty. How did ancient peoples “know” what to do, let alone the Druids? Where did their knowledge come from? And what was the extent of it? My scientific training taught me that observation, experimentation, theory, and more experimentation were the only ways to classify and understand the world. But then there are people like Rupert Sheldrake, a scientist, who talks about morphic resonance, fields which reverberate and exchange information within a universal life force.
Could the Druids, amongst others, “know” when to trepan, could they “know” which herbs to collect, how to prepare medicines from them, see into the future, could they perform “magic”? But at that time I decided this was a step too far for my rational mind, so the Druids in my book are broadly simply clever people who are well read and educated.
And I think I was wrong!
If I had read Elizabeth Lloyd Mayer’s book, Extraordinary knowing: Science, Skepticism, and the Inexplicable, I would have changed my mind, just as she was forced to change hers, moving from a hard scientific paradigm to a much more open minded view. In a book full of challenging examples to the rational of conventional science, there was one example I really liked. The very successful brain surgeon who waited by the head of the patients he was scheduled to operate on until he “saw” a white light; it might take minutes, or hours, but when he saw the light, he knew his operation would be successful. His difficulty was, how to teach the technique to medical students and other surgeons, so he didn’t, because he would have been laughed at, ridiculed, after all, everyone knows that medical science doesn’t work like that!
Or can it?