Basil Valentine's Twelve Keys of alchemy is among the most notorious alchemical works ever crafted. Originally written at the very end of the 16th century, it was almost immediately rendered into English and widely regarded. Containing a series of parables and metaphors regarding the process of creating the Philosopher's Stone, the Twelve Keys claim that alchemy is both real and potent, able to perfect matter and create a medicinal elixir beyond comprehension. Valentine swears that the process is not as others have described, with often vague references to "special" salt and sulfur, but is far easier and much less expensive than claimed in prior works.