As to the kinetic theory of electricity, light, and other physical forces, we certainly know that kinetic effects attend the manifestation of these forces; and where there is no physical matter present we have predicated an ether to serve as a substratum for these kinetic effects. But is that the same as saying that electricity and light are modes of energy or forms of motion? Later research has shown us that these physical forces are attended, not only by kinetic effects, but also by those other effects which we denote by such terms as "mass," "inertia," or "substance." Again, are we entitled to say that electricity, light, etc., _are_ substances, or forms of matter? It would seem more reasonable to say that both energy and mass are to be classed among the effects or accompaniments of electricity and light, electricity and light themselves being something that is neither energy nor mass but parent to both. In brief, the life or _vis viva_ of the physical universe escapes observation and analysis, while its various effects, appearing in the forms which we describe as light, heat, electricity, etc., are defined by us in terms of our two mental concepts "mass" and "energy." The farthest limit to which physical observation has reached, or seems likely to reach, is that of minute and extremely active particles, whose motions are attended with luminous, thermal, and electric phenomena. To put the matter in a nutshell: we find that the so-called inert matter of the universe is composed of what are to all intents and purposes small beings, very much alive and endowed with proclivities. Given our electron or magneton, we are obliged to take for granted its innate properties of energy, etc., for we have no means of explaining them except by reducing them to smaller factors of precisely the same kind--and this is no explanation. That is, we have to assume the universal presence of active and purposeful life--for that is what it amounts to, whatever names we may give. And behind all this manifestation of life there of course lies _mind_; otherwise we must suppose the existence of causeless and purposeless life--a conception which is highly arbitrary and unnecessary.