"The natural principles in the mines are mercury and sulphur. All metals and minerals whereof there be sundry and diverse kinds are begotten of these two. But I must tell you that nature always intendeth and striveth to the perfection of gold. But many accidents coming between change the metals, for according to the purity and impurity of the two afore said principles, mercury and sulphur, pure and impure metals are engendered. Sulphur is not the last amongst the principles because it is a part of the metal. Yea, and the principle part of the philosopher's stone, and many wise men have left in writing diverse and very true things of sulphur. For the blood of sulphur is that inward virtue and dryness which congeals quicksilver into gold, and imparts health and perfection in all bodies."