The Canon's Yeoman's Tale!

I was really excited to read a tale about alchemy, because let's face it, alchemy is cool. Unfortunately for these guys, alchemy (while cool) isn't exactly lucrative, and they are broke. I find it interesting that these characters are new (?) to the crew; it adds a layer of detail that somehow authenticates the journey. The detail of the ingredients they use is a specific thing that seems to validate these guys as "alchemists", although the Yeoman basically admits that their so-called skill isn't quite as legit as they'd like people to believe. The moral of this story is along the lines of not taking what you have for granted, and not looking for the greener grass. Perhaps it also wants to tell the reader to not trust "magic", because God gives us what he wants us to have. One final thought: I struggled with why alchemy is okay and witchcraft wasn't, but I guess it's because alchemy is science-ish and witchraft is satanic?