This process is alchemy: its founder is the smith Vulcan.
The dreams which reveal the supernatural are promises and messages that God sends us directly: they are nothing but His angels, His ministering spirits, who usually appear to us when we are in a great predicament.
The art of healing comes from nature, not from the physician. Therefore the physician must start from nature, with an open mind.
For one country is different from another; its earth is different, as are its stones, wines, bread, meat, and everything that grows and thrives in a specific region.
Once a disease has entered the body, all parts which are healthy must fight it: not one alone, but all. Because a disease might mean their common death. Nature knows this; and Nature attacks the disease with whatever help she can muster.
What the eyes perceive in herbs or stones or trees is not yet a remedy; the eyes see only the dross.