Passing, now, from the consideration of the influence of emotion upon motility, we proceed to examine the interesting series of phenomena resulting from the operation of the same influence upon sensation. Ever tending to be confounded with the converse succession of events, the influence of morbid states of sensibility in producing emotional disorder, its consideration requires more discrimination than that of the previous section. We can scarcely avoid employing language which is not strictly scientific, and can be only understood in a popular sense. Indeed, with two elements so closely allied as the emotional and sensational—mental feeling and bodily feeling (so-called)—it must constantly happen that in our terms, as in reality, we confound the two together, and in this blending fail to discover which is cause and which is effect, or speak of the consciousness of bodily pleasure and pain as if it were not a mental state. It is, however, perfectly easy, in spite of metaphysical difficulties of this kind, to make clear what is meant by the influence of a powerful emotion upon sensation as a part of that influence of the mind upon the body, which we are endeavouring in these papers to point out and illustrate. For example, there can be no question as to the fact that moral disgust does in some instances cause the sensation of nausea, or that distress of mind may occasion neuralgia, or fright the sensation of cold, or that the special senses may, under fear, be stimulated centrally, so as to cause subjective sensations, whether olfactory, visual, or auditory. These facts remain of interest and importance, although the bare statement of them suggests some questions of difficulty. They are so, whether our physiology regards the functions of the hemispherical ganglia as comprising the sensational as well as the ideational elements of the passions—(see ante, July, 1870, p. 174)—or whether it relegates the former to the sensory ganglia. They are so, although not only do mental and physical sensations merge imperceptibly into each other—for we constantly witness the same results from emotional as from sensational excitement, physical and corporeal pain alike acting upon the body (as, e. g., in quickening the circulation)—but mental sensations are so united with their associated ideas that it is difficult to separate the purely emotional from the ideational elements of passion. It is a penalty which we pay for our classifications and divisions that, however convenient they are up to a certain point, they sometimes lead us to do violence to nature; to dissever that which is inseparable, to sacrifice in the present case, it may be, the intimate cohesion of psychical states to the idol of reducing everything in science to orders and classes.
Illustrations of the Influence of the Mind upon the Body, in Health and Disease, Designed to Elucidate the Action of the Imagination