Substantial Nature of Magnetism Author:Helena Petrovna Blavatsky 1921. Madame Blavatsky, founder of Theosophy, discusses the differences between the teachings of Occultists and Theosophists and those of the Substantialists. At the same time, she indicates the agreement of these groups in the matter of magnetism. Magnetism is substantial, the action of a real fluid substance.