Gold, thus exalted, radically penetrates, tinges, and fixes metals." The alchemists generally likened the work to be performed by their agent to the killing of a living thing.

They constantly use the allegory of death, followed by resurrection, in describing the steps whereby the Essence was to be obtained, and the processes whereby the baser metals were to be partially purified.

They speak of the mortification of metals, the dissolution and putrefaction of substances, as preliminaries to the appearance of the true life of the things whose outward properties have been destroyed.

For instance, Paracelsus says: "Destruction perfects that which is good; for the good cannot appear on account of that which conceals it." The same alchemist speaks of rusting as the mortification of metals; he says: "The mortification of metals is the removal of their bodily structure....

The mortification of woods is their being turned into charcoal or ashes." Paracelsus distinguishes natural from artificial mortification, "Whatever nature consumes," he says, "man cannot restore.