Have I, then, any theory to offer as to the nature of this power of life which is essentially new to physiology and biology? I believe that I have—not new as to facts, but as to the interpretation of facts (the latter remain the same on either theory).
In order to make the theory which follows plain in as few words as possible, it will be necessary to refer for a moment to the current conception of vital energy—of life—in the human body. It has been stated by Bergson himself with admirable clearness (Hibbert Journal, October 1911, pp. 35-36; Creative Evolution, pp. 253-54, etc.), and is briefly this:
Food, when broken down and oxidised in the body, gives forth or liberates energy—just as coal liberates energy when burned in the engine. In both cases energy (contained in the food or the coal, as the case may be) is liberated, and this energy is utilized to drive our engine—the human body or the steam-engine (it makes no difference to the argument). The energy thus gained is, it is contended, again given off as heat and work—muscular and mental work in the case of the human engine (the body); mechanical work of all sorts, and heat, in the case of the steam-engine. Thus one is essentially no more mysterious than the other—the body no more so than the steam-engine—vitality no more so than steam! Both are "physical" energies, subject to the law of conservation, and as such transmutable one into the other. This is the generally accepted theory, which likens the human body to a steam-engine, and is the theory all but universally adopted by scientific men, held as proved and adopted without question by M. Bergson!
But such a view of the case is, I believe, essentially untrue. It is one interpretation of the observed facts, truly; but not the only interpretation. The facts remain equally true on either theory; the difference lies in their explanation. It is the old error of confusing coincidence with causation—and not only that, but a particular kind of causation, and "treating it as the only imaginable kind." Just as the psychologists reasoned upon the acknowledged facts of the relation of brain and consciousness; so do the physiologists, in our own day, reason upon this question of the causation of vital energy by food. In both cases there has been one-sided and partial reasoning.
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.
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.
The facts upon which the current theory is founded are well known, and, apparently, thoroughly established. Briefly, they are these: So much food, oxidised or burned outside the body, can be shown to yield so much heat and energy. The same foods, oxidised within the body, yield approximately the same amount of energy. Further, the energy which the body expends (in conscious and unconscious muscular activity, thought, emotion, and as heat, etc.) is, it is contended, practically equivalent to the energy which is thus supplied. There is, therefore, an equivalence, a balance, between income and outgo of energy: so that the recently conducted experiments in calorimetry are held to prove beyond question the causation of vital energy by food.
I shall not in this place stop to question the accuracy of the figures obtained—to point out that the results do not always tally; that far too little allowance has been made for mental and emotional states, etc. I shall assume that the figures are accurate and prove all that they are held to prove. The question then arises: Do the figures prove the causation of vital energy by food? Apparently they do, no doubt, and they are held to do so by the majority of experimental physiologists; but I do not believe that this is at all the case. Admitting the facts, admitting far greater accuracy than the figures really show, we have to consider the question of their interpretation. And this brings us back to the remarks made at the beginning of this paper—that coincidence does not prove causation; and that the same set of facts may often be interpreted in an entirely different manner—one which would show that life is not directly dependent upon food combustion at all, as is generally supposed. The alternative method of interpreting the facts would be as follows: