"Mineral bodies are vapors which have coagulated in nature in the course of long lapses of time, and the first things which coagulate are quicksilver and sulphur, for these and not water or oil (oleum) are the elements of minerals, for the first... (quicksilver) is generated from a water and the other (sulphur) from an oil. Upon these things there operates a gentle digestion constantly with heat and moisture until they are solidified and from them (metallic) bodies are generated by gradual mutation in thousands of years. For if they remain in their minerals, nature purifies them until they arrive at a kind of gold or silver. But by the subtlety of the artist, transmutation of this kind is made in one day or in a brief space of time."