It has to be Alchemy of Herbs. It's about herbalism. I don't even know the actual contents of the book because I stopped reading after page 2 of the introduction, where the author says that she bases all of her practice (that is, her herbal remedies) on the humoral theory of medicine, since that is the framework in which herbalism was developed. YIKES.
(Also, I hope it's OK that I reply to a somewhat old post. I remember it used to be a big no-no, but things seems still a bit slow in here...)