A difference between what? Between receipt and expenditure. Let us, in order to show this clearly, take a point at which the destructive and constructive activities exactly balance one another, a condition corresponding to the neutral or indifferent state of psychologists, and let us represent the same by the numerical formula 50 = 50. At a subsequent point of time the destructive activities predominate; let us suppose them equal to 60, while the value of the constructive falls to 40. On comparing the second moment with the first, we find a negative difference of -20, whose psychic equivalent is a painful state of consciousness. Let us then suppose a third moment, when the constructive activities are in the ascendent and equal 60, while the destructive fall to 40; there will be a positive difference of +20, whose psychic equivalent is a pleasant state of consciousness. I must beg the reader to take all this only by way of illustration.
Thus understood, the “transformation” of pleasure into pain, and pain into pleasure, is only the translation into the order of affective psychology of the fundamental rhythm of life. The latter reduces itself to the ultimate fact of nutrition, consisting of two mutually interdependent processes, one of which implies the other, assimilation and dissimilation. Except in extreme cases, such as inanition and exhaustion on the one hand, and plethora on the other, in which one of the two processes prevails almost without counterpoise, they usually oscillate on either side of a medium, as pleasure and pain do on either side of an alleged neutral state. In physiology it happens that a very clear and easily verified phenomenon covers and hides a contrary phenomenon, so that the principal part of the occurrence is erroneously taken for the whole. Thus one knows that a muscle is heated by exercise, which seems to contravene the law of the transformation of energy, as the mechanical work done ought to consume a part of that mode of motion which we call heat. Béclard and several others after him have shown that there is a real lowering of temperature at the beginning of positive work, and that two opposite phenomena appear in the muscle when in action: one physical, absorbing heat and determining a cooling of the active muscle; the other chemical, producing a heating of the muscle. The latter masks the former. In the same way, the well-known experiments of Schiff have shown that the brain is heated when it receives impressions and elaborates them; it ought to grow cold, since it is doing work; but Tanzi’s experiments seem to establish the existence of alternating oscillations of cold and heat while the brain is at work. We recall these facts, though not in direct relation to our subject, to show that the coexistence of two opposite processes, the most apparent of which conceals the other, is not a chimera. There are frequently two simultaneous phenomena, of which the one is seen and not the other.
According to this hypothesis, then, the conditions of existence of pleasure and pain are implied the one by the other, and always coexistent. What is expressed by consciousness is a surplus, and what is called their transformation is only a difference in favour of one or the other.[[39]]
I add some final remarks on the so-called transformation of pain into pleasure. Being rarer than its opposite, it presents some peculiarities to be noted.
Very acute pleasures exhaust quickly—a condition very favourable to the rapid appearance of pain; I do not see that acute pain ever changes into pleasure, except perhaps in a few cases to be examined in the following chapter.
The “transformation” does not take place abruptly, but always by a gradual transition.
Some have attempted to explain it by habit; but this is so general a term as to require fresh definition in each individual case. It has also been said that the painful sensation, being accompanied by disorganisation and lowering of the vital power, produces, ipso facto, an organic repair, a vital increase, which is the essential condition of pleasure. But this does not prove that the period of reintegration coexists with the first impression and imparts to it a contrary affective sign. The novice in the use of tobacco is at first incommoded by headache, nausea, etc.; then there follows a period of repair, but it is not directly connected with the act of smoking.
It seems to me preferable to admit, with Beaunis, that the agreeable states we speak of are not simple but complex, consisting of a certain number of elements. “It may happen that, among the elements which compose sensation, some are agreeable and some painful; with habit and exercise the painful element gradually disappears from the consciousness, and only the agreeable elements of the sensation remain. In this case there would not really be a transformation of the pain into pleasure, but an extinction, a disappearance of the disagreeable elements of the sensation, and a predominance of the agreeable ones.”[[40]]
The cause of this change seems to me to lie in the biological function called adaptation, of whose true nature very little is known, and which appears to reduce itself to nutritive modifications. Experiment shows that its efficacy cannot be depended on: it succeeds in some persons, but fails in others.