Universal Gravitation. In order to further develop and establish this point we will now consider the subject of Electricity as a Mode of Motion. [Footnote 21: _Mag. and Elec._] CHAPTER VIII AETHER AND ELECTRICITY ART. 79. _Electricity, a Mode of Motion._--The question as to What is Electricity? is one of the greatest problems of modern times. In view of the electro-magnetic theory of light, however, science is able to give a better definition as to what electricity is, than it was able to do previous to the introduction of the theory by Maxwell, and its practical establishment by Hertz. If that theory teaches us anything at all with regard to the nature of electricity, it teaches us that electricity is due to certain motions of the universal Aether, that not only fills all so-called Space, but surrounds all particles and atoms of all Matter. The question has been asked by various scientists, "Is Aether Electricity, or, in other words, are Aether and Electricity one and the same?" Let us look at the question from the standpoint of the analogy from the phenomena of light and heat. As we have already seen (Art. 61), heat is due to a particular kind of motion of the universal Aether, generally known as vibratory motion, which motion is communicated to the Aether by a luminous or heated body. So that we learn that heat at any rate has an aetherial basis, as it is a particular kind of aetherial motion. From Art. 70 we learn also that light is due to an undulatory or wave motion in the Aether; the waves, however, in this case being shorter, and of more rapid vibration than those waves which give rise to heat. Thus light and heat both have an aetherial basis, being due to vibrations of that medium. From these analogies, therefore, we come to the conclusion that electricity and magnetism have an aetherial basis, and are also due to certain kinds of motion in the Aether. That motion may be rotatory motion or vibratory motion, as the case may be, but whatever definition we give of electricity, we cannot as yet say definitely that Aether is electricity.