Restricting our attention to man, and not occupying ourselves with the antagonism between the individual and the race, we shall find that there are cases very difficult to bring under the law. A grain of sand in the eye, an attack of dental neuralgia cause a degree of pain enormously out of proportion with the amount of organic injury sustained. On the other hand, the dissolution of certain organs essential to life is frequently almost painless. The brain may be cut and cauterised almost without suffering; a cavity may be formed in the lung, a cancer in the liver, without the slightest warning of danger. Pain, that “vigilant sentinel” of the advocates of final causes, remains dumb, or only warns us when the evil is already of long standing and irremediable. Nay, more, it often misleads us as to the actual seat of the disease. Examples of false localisation abound; an irritation in the nose is due to intestinal worms, a headache to a morbid condition of the stomach, a pain in the right shoulder to liver complaint. Many other instances of this kind have been studied by physicians under the names of painful synæsthesia, or synalgia. Schneider is, I believe, the only one who has attempted to explain these deviations from the generally admitted formula,[67] by reducing the problem to the two following questions:—First, whether the development of an acute sensibility of the internal organs—_i.e._, a relation of causality between their lesions and the feeling of pain—is, in general, possible; secondly, whether, such development having taken place, this faculty of feeling, as pain, any lesion of the internal organs could be a means of protection, as it is found to be in the case of the skin. The internal organs are only in contact with an interior surface, which is tolerably uniform; if an opposite state of things arises, _i.e._, if they are laid bare by some profound lesion, death ordinarily ensues, at least in animals and in primitive man. Only the slow progress of surgery has made it possible to remedy such accidents. If, through spontaneous variation, a case of sensibility of the internal organs had ever occurred, it would be useless; it could neither become permanent nor be transmitted to descendants, since the lesion, resulting in death, would render the further evolution of this quality impossible. Besides, had this sensitive faculty of the internal organs existed, it must have remained useless, since it could only become efficacious when combined with protective and retractile movements of the organs, which, by the very constitution of the animal, cannot take place. In fact, the whole of the sensibility has been concentrated in the exterior parts of the body, which, by protecting themselves, also protect, in the degree to which this is possible, the internal organs. ----- Footnote 67: _Freud und Leid des Menschengeschlechts_ (1883), pp. 35 _et seq._ -----