If you're interested in why anyone would draw things like this, give Jung a read. His "Alchemical Studies" is chock full of diagrams, in addition to in depth explanations of the symbology and relations between the figures. It's mythological and religious in nature. The alchemists were kind of like nascent scientists, and it's extremely interesting to see how people back then thought. Fair warning: the rabbit hole goes very, very deep (you should probably read a few other works by him first for any of this to make sense: Symbols of Transformation and Archetypes of the Collective Unconscious), so just be prepared for the long haul.