2019 Reprint of 1900 Edition First Published in The Century Illustrated Monthly Magazine, Volume LX, June, 1900. Full facsimile of the original edition, not reproduced with Optical Recognition software. In this short essay Tesla speculates on the nature of man and energy. "Though we may never be able to comprehend human life, we know certainly that it is a movement, of whatever nature it be. The existence of movement unavoidably implies a body which is being moved and a force which is moving it. Hence, wherever there is life, there is a mass moved by a force. All mass possesses inertia, all force tends to persist. Owing to this universal property and condition, a body, be it at rest or in motion, tends to remain in the same state, and a force, manifesting itself anywhere and through whatever cause, produces an equivalent opposing force, and as an absolute necessity of this it follows that every movement in nature must be rhythmical." Illustrations include burning the nitrogen of the atmosphere, a diagram of the three ways of increasing human energy, the first practical Telautomaton, an experiment to illustrate the supplying of electrical energy through a single wire without return, the experiment to illustrate the transmission of electrical energy through the earth without wire, a photographic view of the coils responding to electrical oscillations, a view of the essential parts of the electrical oscillator used in the experiment, an experiment to illustrate an inductive effect of an electrical oscillator of great power, the experiment to illustrate the capacity of the oscillator for producing electrical explosions, an experiment to illustrate the capacity of the oscillator for creating a great electrical movement, a photographic view of an experiment to illustrate the effect of an electrical oscillator delivering energy at a rate of seventy-five thousand horse-power, and small diagrams of wireless telegraphy mechanically illustrated, and obtaining energy from the ambient medium.