when Mercury has been matured, developed, and perfected, that it is
able to transmute inferior metals into gold. The essential thing to do
is, therefore, to find an agent which will bring about the maturing
and perfecting of Mercury. This agent, Philalethes calls "Our divine
Arcanum."

Although it appears to me impossible to translate the sayings of the
alchemists concerning Elements and Principles into expressions which
shall have definite and exact meanings for us to-day, still we may,
perhaps, get an inkling of the meaning of such sentences as those I
have quoted from Basil Valentine and Philalethes.

Take the terms _Fire_ and _Water_. In former times all liquid
substances were supposed to be liquid because they possessed something
in common; this hypothetical something was called the _Element,
Water_. Similarly, the view prevailed until comparatively recent
times, that burning substances burn because of the presence in them of
a hypothetical imponderable fluid, called "_Caloric_"; the alchemists
preferred to call this indefinable something an Element, and to name
it _Fire_.

We are accustomed to-day to use the words _fire_ and _water_ with
different meanings, according to the ideas we wish to express. When we
say "do not touch the fire," or "put your hand into the water," we are
regarding fire and water as material things; when we say "the house is
on fire," or speak of "a diamond of the first water," we are thinking
of the condition or state of a burning body, or of a substance as
transparent as water. When we say "put out the fire," or "his heart
became as water," we are referring to the act of burning, or are using
an image which likens the thing spoken of to a substance in the act of