Page:Popular Science Monthly Volume 15.djvu/58

 diverted. But the circumstances attending the operations with the laughing gas were again calculated to absorb the attention in other directions and thus divert it from the shoulder. The result was the immediate relaxation of the muscles involved in maintaining the shoulder in a fixed position. In the absence of any local disease which could cause local irritation and reflex muscular contraction, this must have been kept up by direct volition. An important evidence of its voluntary character, besides that which is afforded by the prompt relaxation through opposite mental influence, was the immediate and very great improvement in the patient's general health. She was, in fact, completely exhausted by a labor which she was not conscious of doing, but when she ceased this continuous effort she at once improved in strength. The same improvement in the general health, but in an even more marked degree, was manifested in the second case above related.

Adult life is not alone liable to the class of mental influences which we are now discussing. Young persons and even quite small children are frequent subjects for psycho-biological study.

But mental influence over bodily function is exhibited not alone in connection with the muscles in determining their relaxation or rigidity, in certain cases; but what are called bodily sensations are even more dominated by the mental timbre of the individual. We have local and general hyperæsthesias and anæthesias both as transient and as permanent conditions from this cause. I feel obliged to employ phrases as they are employed in common use, but, strictly speaking, there are no bodily sensations, for all sensation is mental—there is and can be no other. The most that we can strictly say is that we feel in the mind, but refer the cause of such feeling to certain locations in the body. Stick a pin in my flesh, and whether I feel it or not, and how much I may feel it, will depend wholly on the state of my mind. If obscured by an anæsthetic or if asleep, provided the impinging on the nerves is not sufficient to waken me, or even if my attention be very much absorbed, I shall not be conscious of the pricking. On the other hand, if I have been pricked before so that my fears are aroused, or if I am worried or weary or ill, then the pain is many hundred times greater than under the opposite circumstances. We go to a dentist one day when we are in a hurry, and with the mind troubled about some matter. The drilling of his little instrument is agony. We leave and return the next day with plenty of time, and our business settled. The dentist drills still deeper into the same cavity while we sit in comparative comfort.

But not only the same person has different degrees of sensation at different times, according to his mental timbre at the time, but different individuals and different classes of persons feel both pleasures and pains more or less according to their individual or class elevation in the intellectual scale. If a knife were thrust into the flesh, in corresponding locations and to the same depth, in twenty people, no two would feel