Basil Valentine then deals with the formation of the three Principles of things, by the mutual action of the four Elements.  Fire acting on Air produced Sulphur; Air acting on Water produced Mercury; Water acting on Earth produced Salt.  Earth having nothing to act on produced nothing, but became the nurse of the three Principles.  “The three Principles,” he says, “are necessary because they are the immediate substance of metals.  The remoter substance of metals is the four elements, but no one can produce anything out of them but God; and even God makes nothing of them but these three Principles.”

To endeavour to obtain the four pure Elements is a hopeless task.  But the Sage has the three Principles at hand.  “The artist should determine which of the three Principles he is seeking, and should assist it so that it may overcome its contrary.”  “The art consists in an even mingling of the virtues of the Elements; in the natural equilibrium of the hot, the dry, the cold, and the moist.”

The account of the Elements given by Philalethes differs from that of Basil Valentine.

Philalethes enumerates three Elements only:  Air, Water, and Earth.  Things are not formed by the mixture of these Elements, for “dissimilar things can never really unite.”  By analysing the properties of the three Elements, Philalethes reduced them finally to one, namely, Water.  “Water,” he says, “is the first principle of all things.”  “Earth is the fundamental Element in which all bodies grow and are preserved.  Air is the medium into which they grow, and by means of which the celestial virtues are communicated to them.”

According to Philalethes, Mercury is the most important of the three Principles.  Although gold is formed by the aid of Mercury, it is only 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.