Lead, tin, iron, or copper is calcined. The prominent and striking feature of these events is the disappearance of the metal, and the formation of something very unlike it. But the original metal is restored by a second process, which is like the first because it also is a calcination, but seems to differ from the first operation in that the burnt metal is calcined with another substance, with grains of wheat or powdered charcoal. Led thereto by their theory that destruction must precede re-vivification, death must come before resurrection, the alchemists confined their attention to one feature common to all calcinations of metals, and gave a superficial description of these occurrences by classing them together as processes of mortification. Sulphur, wood, wax, oil, and many other things are easily burned: the alchemists said, these things also undergo mortification, they too are killed; but, as "man can restore that which man has destroyed," it must be possible to restore to life the thing which has been mortified. The burnt sulphur, wood, wax, or oil, is not really dead, the alchemists argued; to use the allegory of Paracelsus, they are like young lions which are born dead, and are brought to life by the roaring of their parents: if we make a sufficiently loud noise, if we use the proper means, we shall bring life into what seems to be dead material. As it is the roaring of the parents of the young lions which alone can cause the still-born cubs to live, so it is only by the spiritual agency of life, proceeded the alchemical argument, that life can be brought into the mortified sulphur, wood, wax, and oil. The alchemical explanation was superficial, theoretical, in the wrong meaning of that word, and unworkable. It was superficial because it overlooked the fact that the primary calcination, the mortification, of the metals, and the other substances, was effected in the air, that is to say, in contact with something different from the thing which was calcined; the explanation was of the kind which people call theoretical, when they wish to condemn an explanation and put it out of court, because it was merely a re-statement of the facts in the language of a theory which had not been deduced from the facts themselves, or from facts like those to be explained, but from what were supposed to be facts without proper investigation, and, if facts, were of a totally different kind from those to which the explanation applied; and lastly, the explanation was unworkable, because it suggested no method whereby its accuracy could be tested, no definite line of investigation which might be pursued.