To place the theory in as clear a light as possible, then, it is this: Food supplies or replaces broken-down tissue (and heat) to the body; but not vitality, or the power of life, which comes only from rest and sleep. No matter how much food we may eat and perfectly oxidise, there comes a time, nevertheless, when we must go to bed, and not to the dining-room, to recuperate our strength and energies. During sleep, vital energy flows into us (our nervous systems), and all animals need sleep--this fact differentiating them, at once, from any form of mechanical engine. Life, vital energy, is not due, as is universally thought, to chemical combustion, but to vital replenishment. No energy is _created_ within the body; it is merely _transmitted_. The body, in fact, acts as a means of transmission--as a sort of "organic burning glass" which transmits and focuses the sun's rays on one focal point. And just as any crack, or blur, or clouding, or other accident to the burning glass would interfere with its power and capacity from transmitting the rays, so, any accident or disease or pathological state of the organism would interfere with or altogether prevent the passage or flow through it, of the life or vital energy. "The more perfect, the better these conditions, the greater the influx of vital force, and vice versa. We must see that all the electrodes and avenues and channels are bright and clear, so that there shall be as little hindrance as possible to either the inflow of energy in the form of power, or to its outflow in the form of work done." My theory of the relation of body and bodily energy is, in fact, an extension of James' "transmission theory" of consciousness to the _whole_ of our life and vital energy. And I believe the one is as defensible as the other. But, I shall be asked, is there any evidence for such a theory? There is much evidence, there are many facts, which I have adduced in full elsewhere.[16] This is not the place to discuss the physiological intricacies involved, and I can only refer those interested to the work in question. At present, I shall assume its accuracy--or at least its validity--and proceed to show in few words why it is that this theory is not contrary to any known facts, but is capable of explaining them just as fully as the generally accepted theory, and other (disputed) facts far more readily.