As has been said so many times before, Thales was the first to call attention to the fact that amber (fossilized resin), when rubbed with wool or fur, possesses the curious property of attracting small particles, such as straw, pith, lint, dried leaves, etc.;—though there is no reason to suppose that he was the discoverer of this phenomenon. He called the amber _elektron_; and today we call the indivisible corpuscles, or natural unit charges of negative electricity, _electrons_—the true _atoms_ of electricity. But hard rubber, or sealing-wax, is just as “mysterious” as the lodestone (magnetite—natural magnetic iron). Rub the sealing-wax with fur, and it will exhibit all the peculiar properties of the lodestone. Rub glass with silk, and it, too, becomes a lodestone in effect. The ancient Greek philosophers could not explain these phenomena in precise terms. Empedocles (born between 500 and 480 B. C.) accounted for the attraction of iron to the magnet on the hypothesis that “emanations” or “effluences” from the magnet penetrate into the “symmetrical pores” of the iron, drawing the iron itself and holding it fast. The concept “electricity” was unknown to the Greeks. But it is possible that Empedocles had in mind some such “effluence” or “emanation” as the “fluid” electricity of Benjamin Franklin (1706-1790) and his successors. The soul-force (“moving power”) of Thales—always moving and causing movement—and the “effluences” of Empedocles have become the “field of force” of Faraday, Sir J. J. Thomson, and Sir Oliver Lodge. The self-moving “soul” of nature, manifest in the lodestone, or acting on the lodestone, or on the particles said to be “attracted” by the lodestone, is but a synonym for the lines of force of the magnetic field of modern physics. Thales and Empedocles spoke in the language (terminology) of their day and age. The “emanations” of Empedocles are the “corpuscles” of Thomson—a body becoming positively electrified by “losing some of its corpuscles”, and hence capable of drawing negatively charged particles to itself. Electricity and magnetism are related but not identical. A moving magnet can induce an electric current in a wire, and an electric current can produce magnetism in iron. The construction of telegraph and telephone instruments depends on the fact that an electric current can produce magnetism and that magnetism can produce an electric current. We know _effects_ which we call “electricity”, just as we know the phenomena associated with living protoplasm without knowing what “life” is. It may be that “life” and “electricity”, as well as “electricity” and “magnetism”, are all different aspects of the same thing. Today we say, in the words of Dr. Charles P. Steinmetz (“Relativity and Space”, Pages 18-19):—