The physical theory of transmutation is based on the composite character of metals, on their generation in the bowels of the earth, and on the existence in nature of a pure and penetrating matter which applied to any substance exalts and perfects it after its own kind. This matter is called THE LIGHT by Eugenius Philalethes and by numerous other writers. In its application to animals, it exalts animals; in its application to vegetables, it exalts vegetables, while metals and minerals, after the same manner, are refined and translated from the worst to the best condition. All the elements which enter into the composition of metals are identical, but they differ in proportion and in purity. In the metallic kingdom, the object of nature is invariably to create gold. The production of the baser metals is an accident of the process, or the result of an unfavourable environment. The generation of metals in the earth is a point of great importance, and must be well studied by the amateur, for without this, and the faithful imitation of Nature, he will never achieve anything successful. It is by means of the seed of metals that their generation takes place. Their composite character indicates their transmutable quality. Such transmutation is accomplished by means of the philosophical stone, and this stone is, in fact, the combination of the male and female seeds which beget gold and silver. Now the matters or elements of this stone, and the _prima materia_ above all, are concealed by a multitude of symbols, false and allegorical descriptions, and evasive or deceptive names. According to Baron Tschoudy, all who have written on the art have concealed the true name of the _prima materia_ because it is the chief key of chemistry. Its discovery is generally declared to be impossible without a special illumination from God, but the sages who receive this divine favour and distinction have occasionally perpetuated its knowledge by the instruction of suitable pupils under the pledge of inviolable secresy. The author of _L’Étoile Flamboyante_ supplies an immense list of the names which have been applied to this mysterious substance under one or other of its phases. “As those that sail between Scylla and Charybdis are in danger on both sides,” says D’Espagnet, “unto no less hazard are they subject, who, pursuing the prey of the golden fleece, are carried between the uncertain rocks of the philosophers’ sulphur and mercury. The more acute, by their constant reading of grave and credible authors, and by the irradiant sun, have attained unto the knowledge of sulphur, but are at a stand in the entrance of the philosophers’ mercury, for writers have twisted it with so many windings and meanders, and involved it with so many equivocal names, that it may be sooner met with by the force of the seeker’s intellect than be found by reason or toil.”