"Let it be for you a great and high mystery in the light of nature that a thing can completely lose and forfeit its form and shape, only to arise subsequently out of nothing and become something whose potency and virtue is far nobler than what it was in the beginning.

"Nothing has been created as ultima materia—in its final state. Everything is first created in its prima materia—its original stuff; whereupon Vulcan [or transmuting fire] comes, and by the art of alchemy develops it in its final substance. . . . For alchemy means: to carry to its end something that has not yet been completed. To obtain the lead from the ore and to transform it into what it is made for. . . . Accordingly, you should understand that alchemy is nothing but the art which makes the impure into the pure through fire. . . . It can separate the useful from the useless, and transmute it into its final substance and its ultimate essence.

"The transmutation of metals is a great mystery of nature. However laborious and difficult this task may be, whatever impediments and obstacles may lie in the way of its accomplishment, this transmutation does not go counter to nature, nor is it incompatible with the order of God, as is falsely asserted by many persons. But the base impure five metals—that is, copper [or Venus], tin [or Jupiter], lead [or Saturn], iron [or Mars], and quicksilver [or Mercury]—cannot be transmuted into nobler, pure, and perfect metals—namely, into gold [or the Sun] and silver [or the Moon]—without a tinctura, or without the philosopher’s stone.
Since ancient times philosophy has striven to separate the good from the evil, and the pure from the impure; this is the same as saying that all things die and that only the soul [of them] lives eternal. The soul endures while the body decays, and you may recall that correspondingly a seed must rot away if it is to bear fruit. But what does it mean, to rot? It means only this—that the body decays while its essence, the good, the soul, subsists. This should be known about decaying. And once we have understood this, we possess the pearl which contains all the virtues.

"Decay is the beginning of all birth. . . . It transforms shape and essence, the forces and virtues of nature. Just as the decay of all foods in the stomach transforms them and makes them into a pulp, so it happens outside the stomach. . . . Decay is the midwife of very great things! It causes many things to rot, that a noble fruit may be born; for it is the reversal, the death and destruction of the original essence of all natural things. It brings about the birth and rebirth of forms a thousand times improved. . . . And this is the highest and greatest mysterium of God, the deepest mystery and miracle that he has revealed to mortal man."

Paracelsus