If, however, we reject the prevalent notion of the causation of vital energy by food, we must have another theory to offer in its place. It is, I know, presumptuous thus to run counter to the whole of accepted teaching, in this respect, and my excuse must be that I believe my theory represents the truth, while that universally held does not! Again, I must emphasize that I speak, not of facts, but of inferences drawn from facts. With this apology, I shall state my own view of the case as follows: Instead of comparing the human body with the steam-engine, it should be compared with and likened to the _electric motor_. Just as the motor is recharged, or receives its energy from some external source, just so, I believe, is the human nervous system recharged from without, during the hours of sleep. It is placed into a peculiar, receptive condition, in which this "recharging" process takes place. Our energy is derived through sleep, and not from food. Food merely replaces broken-down tissue (and, if you will, the animal heat) but never supplies or creates its vital energy. This depends upon its nervous mechanism, and upon sleep, and not upon the muscular system and chemical combustion. What differentiates the steam-engine from the human organism is the fact that one needs sleep while the other does not (in other words, one is living and vital, and the other is not), yet, in spite of this obvious difference--which is so great that it really destroys all the analogy--physiologists have continued to disregard it, and to treat the human body as a mere machine--such as a steam-engine--which requires no sleep, and derives its energy solely by combustion! To my mind, this is one of the most curious paradoxes of modern science.