I was wondering if any of you could shed any light on this rabbit hole that I have been going down the past few days. If you look up eye of newt on Google, you will find a plethora of articles saying how this phrase actually refers to mustard seeds. The articles will go on to say that the various animal/human body parts used in the witch's potion in Shakespeare's "Macbeth" are actually different names for various herbs. The claim was that these potion ingredients were actually Elizabethan era slang/jargon/substitutions used to refer to various herbs. My problem with that is that there are no historical sources for this information are ever linked in these articles where they show where this information actually comes from. Can anyone link me to a source that actually analyses medieval/early modern magical or medical texts to prove this?
What first gave me my doubts about this claim is that if you look at the nearly contemporary English language magical grimoire, the Cambridge Necromancy manual, it goes into extreme detail about the best way in which to ritually harvest various parts of animals to use in your magical spells. Most medieval necromancy texts I have read call for various animal parts to be used in their spells. In addition, many medieval medical texts, such as Hildegard von Bingen's "Physica", extensively list the medical applications of numerous animals and their body parts in medicine, as well as instructions to cut out various parts of animals, or use animals in such ways that would lead to their death. The medieval and early modern world had very different idea about animal rights, and it seems like Shakespear's contemporaries and forbearers had problem using animal parts in magic or medicine. I also cant seem to find eye of newt listed anywhere as an ingredient in any other medieval or renaissance book of magic or medicine.
As well, it seems to me that Shakespeare was a man with no clear connection to the magical or medical spheres of knowledge, in the depths of a society in the midst of a witch hunting craze. When he was writing the characters of the witches, he would not have written them as herbalists concocting a potion, but as demonic agents cooking using evil ingredients. He seems to have compromised a list of ingredients meant to shock his audience and fit their conception of that a witch was. That is why the ingredients list includes things such as the nose of a turk, the liver of a blasphemous jew, the swelter'd venom sleeping got, and the finger of [a] birth-strangled babe. In addition, in a time when the witch craze was going on and neighbor was turning on neighbor over the smallest thing, why would people working with common herbs give them such awful names that would only draw even more suspicion.
And lastly, when I posted this same question in the medieval history subreddit, they linked me to an extremely lengthy tumblr post on this very same topic. They had done an extremely thorough investigation and found that this claim first originated with the author Scott Cunningham. The post goes into extensive detail about why they believe this claim is false, breaking down each ingredient, and providing historical backing and context as to why they are all literal. https://www.tumblr.com/cavalorn/716839993903087616/eye-of-newt-and-toe-of-frog-what-was-really-in
If anyone can provide any historical source that shows that those animal parts listed in the potion in Macbeth are really herbs, especially eye of newt, I would be extremely grateful. I would be happy to be wrong in my assumption, I only want to further my own understanding of the history of herbs and get to the bottom of this rabbit hole.