"If you prudently desire to make our elixir, you must extract it from a mineral root. For as Geber saith, you must obtain the perfection of the matter from the seeds thereof. Sulphur and mercury are the mineral roots, and natural principles, upon which nature herself acts and works in the mines and caverns of the earth, which are viscous water, and subtil spirits running through the pores, veins, and bowels of the mountains. Of them is produced a vapour or cloud, which is the substance and body of metals united, ascending, and reverberating upon its own proper earth, (as Geber sheweth) even till by a temperate digestion through the space of a thousand years, the matter is fixed, and converted into a mineral stone, of which metals are made."