"Let me ask if there is anything marvelous in this statement. On the earth's surface men arrest the fitful wind, and by so doing divert the energy of its motion into movement of machinery; they induce it to turn mills and propel vessels. This motion of air is a disturbance, mass motion transmitted to the air by heat, heat in turn being a disturbance or interruption of pure motion. When men learn to interrupt this unperceived stream of energy so as to change directly into material motion the spirit that saturates the universe, and that produces force expressions, as it is constantly rushing from earth into space, and from space back again, they will have at command wherever they may be an endless source of power, light, and heat; mass motion, light and heat being convertible. Motion lies behind heat, light, and electricity, and produces them, and so long as the earth revolves on its axis, and circles in its orbit, man needs no light and heat from such indirect sources as combustion. Men will, however, yet obtain motion of molecules (heat), and material mass motion as well, from earth motion, without the other dangerous intermediate force expressions now deemed necessary in their production." "Do you wish me to understand that on all parts of the earth's surface there is a continual expenditure of energy, an ever-ready current, that is really distinct from the light and heat of the sun, and also that the imponderable bodies that we call heat, light, electricity, and magnetism are not substances at all?" "Yes," he replied. "And that this imperceptible something--fluid I will say, for want of a better term--now invisible and unknown to man, is as a medium in which the earth, submerged, floats as a speck of dust in a flood of space?" "Certainly," he replied. "Am I to infer from your remarks that, in the course of time, man will be able to economize this force, and adapt it to his wants?" "Yes." "Go on with your exposition, I again beg of you; lead me deeper into this expanding study."