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] Footnote 40: Beaunis, _Sensations internes_, pp. 246, 247. 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. CHAPTER IV. MORBID PLEASURES AND PAINS. _Utility of the pathological method—Search for a criterion of the morbid state; abnormal reaction through excess or defect; apparent disproportion between cause and effect; chronicity—I. Morbid pleasures, not peculiar to advanced civilisation—Different attempts at explanation—This state cannot be explained by normal psychology: it is the rudimentary form of the suicidal tendency—Classification—Semi-pathological pleasures: those destructive of the individual, those destructive of the social order—II. Abnormal pains—Melancholic type—Whence does the painful state arise in its permanent form? from an organic disposition? or from a fixed idea?—Examples of the two cases._