But that for which they principally excited public attention, was their creed respecting certain elementary beings, which to grosser eyes are invisible, but were familiarly known to the initiated. To be admitted to their acquaintance it was previously necessary that the organs of human sight should be purged by the universal medicine, and that certain glass globes should be chemically prepared with one or other of the four elements, and for one month exposed to the beams of the sun. These preliminary steps being taken, the initiated immediately had a sight of innumerable beings of a luminous substance, but of thin and evanescent structure, that people the elements on all sides of us. Those who inhabited the air were called Sylphs; and those who dwelt in the earth bore the name of Gnomes; such as peopled the fire were Salamanders; and those who made their home in the waters were Undines. Each class appears to have had an extensive power in the elements to which they belonged. They could raise tempests in the air, and storms at sea, shake the earth, and alarm the inhabitants of the globe with the sight of devouring flames. These appear however to have been more formidable in appearance than in reality. And the whole race was subordinate to man, and particularly subject to the initiated. The gnomes, inhabitants of the earth and the mines, liberally supplied to the human beings with whom they conversed, the hidden treasures over which they presided. The four classes were some of them male, and some female; but the female sex seems to have preponderated in all.