This fairly beefy alchemical tract (technically two tracts in multiple sections) comes from the Alchemical Museum of Waites’ time, originally penned by Sendivogius in the 1600s. It is strictly physical alchemy at work here, and strictly the more “authentic” path of the same, not like some works which are basically about just creating interesting medicines (few of which were safe!) or counterfeit currencies. Part of this work is in the form of dialogue between the alchemist and his mercury. In that sense it is vaguely like the much later work “On the Philadelphian Gold.”
Here then the major concept of alchemy, that great work, is that of the four elements, three substances, two halves (male and female) thus joined creating the perfected substance that was believed to operate much like stem cells for the mineral world, literally, a sort of primordial material that could be purified out from other things and used to project matter. Importantly, Sendivogius references what some other contemporaries do, namely that this substance, while found in gross (literally vulgar, as in composted feces, etc) matter, to try and work with that same matter improperly will benefit the sage not at all.