This action of the body on the mind through the senses is so continual and familiar that we seldom reflect upon it, although in other instances we are surprised that matter should act upon spirit. Such surprise is expressed when a new drug is discovered which temporarily extinguishes the activity of the mind and produces insensibility. Under the influence of either, chloroform, and laughing gas, patients in hospitals can undergo dangerous operations without being conscious of any pain. This is very wonderful, but not more wonderful than facts of a similar kind with which the world has long been familiar. The temporary cessation of the mind’s power of feeling caused by these drugs is much the same as the effect produced by opium and alcohol. It has long been known to the world that opium can fill the mind with fantastic visions, very different from those that present themselves to the mind in its ordinary state. Still more familiar are the effects of alcohol in producing cheerfulness in some minds, melancholy in others, and in causing complete insensibility when taken in large quantities. Long-continued excess in drinking wine and spirits may even in the end lead to the delusions of insanity.
The same effect may also be caused by a severe blow on the head or by sunstroke. The material of the brain is so intimately connected with thought that the slightest injury to it may produce unconsciousness or entirely mar the intellect. Sometimes the effect of such injuries seems to be extremely capricious, as in the recorded cases in which injury to the brain has blotted out the memory of one particular language, or of one particular division of the parts of speech. In all the cases considered above, a bodily change is the antecedent, and a mental change the consequent. Let us now consider those instances in which a mental change appears to be casually connected with a subsequent bodily change.
Of these the most familiar case is a voluntary motion, in which the movement of our limbs follows a volition formed in our minds. Almost equally familiar are the involuntary changes in our countenance, which express the emotions of joy, grief, anger, and fear; and, by being frequently repeated, permanently alter the features of the human countenance, so that the skilful physiognomies can read our character in our faces. The state of the mind produces marked effects on the condition of the body. The proverb “Laugh and grow fat” expresses the scientific truth that cheerfulness helps us to assimilate our food; and it is known that fear has a prejudicial effect upon the digestion. Wonderful cures have been effected by influencing the mind of the patient. It has often been noticed that fear is a predisposing cause of cholera, and that those who have caught the disease are more likely to recover if they do not despair of recovery. The curative effects of confidence were demonstrated some time ago in the case of another disease, by experiment made with magnets.
In a certain hospital it was observed that the application of magnets had a decidedly good effect upon rheumatism. Some one, who suspected the truth, tried, instead of real magnets, pieces of wood coloured and shaped like magnets, and those were found to be equally effectual. This showed that what really effected the cure of the rheumatism was the confidence produced in the mind of the patient, and that the recovery, which was supposed to be due to the power of the magnet, was really a case of what is called faith-healing. All the cases we have been considering show that there is between mind and body a very close alliance, so that whatever affects the one may be expected to produce an effect upon the other. From this may be deduced a practical lesson of great importance, which is too often not taken to heart by Indian students. It is that, if we neglect the claims of our body in order to devote ourselves more exclusively to the cultivation of our minds, the ill-health of our bodies will impair our intellectual powers, and it is not unlikely that in the end we may ruin mind and body together.