answer:Wikipedia Galen, then go to the references and track them down on the net. You will find references as to his methods and even his teachers and theirs as well. Galen is a good start to move forward in time from. Much of today’s herbal pharmacopea and folk medicine comes from the times when doctors were not available in certain rural areas. The Appalacian culture in the U.S. is an excellent source for these methods. In Europe, during WWII, pharmaceuticals often weren’t available to civilians due to the great military demand. So, the people were forced to revive and research the methods used two generations previously in order to treat many of their maladies. The forests of Europe were foraged thoroughly during this time for the ingredients of old medical recipes. Books were published in order to assist them in the old methods, making the concoctions, and identifying the correct plants. Some of these books still survive. For English texts of this type, I would search the net and contact antique booksellers and information on recent reprints.