[Ill.u.s.tration: Fig. 26 (two dots about two inches apart)]

After an interval four dots will be seen--each of the dots having a picture in each eye. Then only one dot may be seen because the pictures combine. Sometimes three dots will be seen. When the dots swim toward one another, a curious feeling of insecurity comes over the experimenter, showing how much our sense of stability is dependent on vision and ill.u.s.trating why vision from a height is so disturbing because objects cannot be properly fixed on the distant background.

[Ill.u.s.tration: Fig. 27 (from left to right--an empty bird cage, a vertical line, a bird)]

Just as the two dots may be made to come together, so, after a little practice, a bird may be made to go into a cage (Fig, 27) or an apple made to go onto a plate (Fig. 28),

[Ill.u.s.tration: Fig. 28 (from left to right--an apple, a large plate)]

These illusions show how many things that people {768} "see with their own eyes" are not so. All depends on the attention and the state of mind at the time when the seeing is done. In day-dreams these illusions often occur and may be the basis of delusions.

[Ill.u.s.tration: Fig, 29 (Several complex line figures)]

There are, however, a number of optical illusions which ill.u.s.trate certain defects of our vision that cannot be corrected, no matter how much we may desire to see correctly. We continue to see them not as they are but as they seem, and we must correct our vision by information from other sources. The Muller-Lyer lines are familiar and are given here (Fig. 29) because {769} they show how easily the senses may deceive us, even that most acute of our senses, vision, as to the sizes of things.

[Ill.u.s.tration: Fig. 30 ( Two identical figures, one above the other; each is like a funnel cut parallel to its axis and laid flat. )]

Figure 30 ill.u.s.trates how easy it is to be deceived by the juxtaposition of different portions of objects. I have had a woman who had cut out high collars for children and who happened to put them in the juxtaposition of the sketch here given think that she was either losing her sight or her judgment was being affected by the nervous condition in which she was. Nothing would persuade her that some serious development was not taking place until I showed her this ill.u.s.tration. In this illusion the juxtaposition of the short curved line to the long curved line of the other figure produces all the disturbance of judgment of size.

The illusions of filled and unfilled s.p.a.ce are interesting and are quite inevitable. They are due to physiological visual effects and are very strikingly ill.u.s.trated by what is known as the sun and moon illusion. Both these luminaries seem larger at the horizon than they are at the zenith. This is entirely an optical illusion. The horizon seems farther away than the zenith because vision to it is interrupted. The heavens appear not to be a half sphere, but more like an old-fashioned watch gla.s.s.

[Ill.u.s.tration: Fig. 31 (A--a square consisting of closely s.p.a.ces vertical lines; B--a square consisting of closely s.p.a.ces horizontal lines; C--a empty square with only its exterior boundaries.)]

Since the sun and moon occupying the same s.p.a.ce on the retina are, because of this apparent difference of distance, judged to be farther away at the horizon than they are at the zenith, we are inevitably forced to the conclusion that they are larger in size than when in the other position. The over-estimation of filled s.p.a.ce as compared with {770} the unfilled is mainly due to the interrupted muscular action of the eyes in traveling over the s.p.a.ce requiring more effort. This makes it seem longer. Probably physiological processes on the retina also contribute to the illusion. A series of objects, even dots, will cause a greater physiological excitation of the retina than an equal amount of s.p.a.ce, the boundaries of which alone are brought to our attention.

Illusions of size are even more startling than illusions of distance.

It is perfectly possible to take three s.p.a.ces, each exactly a square inch, and by drawing lines in two of them in different directions to make the figures appear of {771} very different size. This is a rather disturbing illusion, particularly for women who are apt to think that perpendicular lines make them appear tall and thin, while horizontal lines have the opposite effect. This is true if the lines are not placed quite close together. The reason why women wear many ribbons, however, whether they themselves recognize it or not, is that the attraction of attention to these makes the s.p.a.ce in which they are seem longer. Hussars are dressed in uniforms with many rows of gilt cord or braid running across their chests in order to increase their apparent height. As a rule, a cavalry man must not weigh over 140 pounds or his horse will break down in long, forced marches. Such men are often of small stature and their apparent height must be increased by their uniform, so as to make them look formidable. Advantage is taken of this optical illusion of filled s.p.a.ce to produce this effect.

[Ill.u.s.tration: Fig. 32 (several complex curved figures,)]

Other illusions of size are quite frequent. It is rather hard for the ordinary observer to think that the half circles, _a_ and _a'_ (Fig.

32), are the same size, or that _b_ and _b'_ in the same chart are the same curve. The interruption in the circles _c_ and _c'_ produce very curious erroneous impressions which require a knowledge of this illusion to correct.

Optical illusions with regard to directions of lines are extremely common. Quite unconsciously we translate directions into special meanings. This is what enables perspective to be effective in drawings. It has many disturbing features, however. Some of these are striking ill.u.s.trations of the defects of our vision.

[Ill.u.s.tration: Fig. 33 (tall, narrow rectangles covering diagonal lines pa.s.sing under them.)]

[Ill.u.s.tration: Fig, 34 (a large black square with several parallel diagonal white lines; each diagonal line has several intersecting lines; the upper left diagonal has horizontal intersecting lines, the next diagonal has vertical intersections; etc.)]

Poggendorf's ill.u.s.tration of the displacement of oblique lines (Figure 33) {772} and Zollner's distortion of parallel lines as ill.u.s.trated by Figure 34, make it very clear that our judgment of direction must depend on many factors besides our vision, if we are not to make serious mistakes.

These optical illusions might seem to be of little significance, but the Greeks thought them of so much importance and recognized so thoroughly that they could not be corrected, and that the distortions and displacements would inevitably take place, that they deliberately put certain optical corrections into their great architectural monuments in order to avoid these false appearances. These have been traced very accurately in the Parthenon, for instance. In a word, the Greeks, knowing of these optical illusions, in order to make the lines of their buildings appear correct, deliberately made them wrong to a sufficient degree to correct the optical illusion; This frank mode of yielding to a limitation of human nature is a fine lesson for patients to learn if they can only be made to learn it from these ill.u.s.trations.

It is with regard to colors, however, that we have the best examples of optical illusions depending on the individual and his special anatomy and physiology. Color-blind people are quite sure that they see color, just as other people do, until their defect is demonstrated to them. A man who is color blind for red thinks that he sees that color as other people do, while all that he sees is a particular shade of brightness which, because other people call it red, he has come to call red. When asked to pick out red from a series of other colors he may often succeed. When asked, however, to take a skein of red wool selected for him to a basket containing a number of different colored wools, and to bring back all those that are of the same color, he will select grays and browns and sometimes greens as well as reds, and present them as all matched colors. A man who is color blind for all colors will still think that he sees colors as other people do. The ingenious ill.u.s.tration of the American flag as it appears to people suffering from different forms of color blindness, though they are all persuaded that they see the same kind of flag, is an interesting example of how different may be people's sensations, though their conclusions are the same. It may be seen in many of the text books of a.n.a.lytical or experimental psychology.

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Dalton, to whom we owe the atomic theory, was himself color blind for red and made the first investigations in that subject. He was of Quaker origin and found that a great many of his brethren were deficient in color vision. It becomes much easier from this to understand why they resolved to wear nothing but gray. They did not see colors as other people do and therefore could not understand nor sympathize with the joy of other people in color. Dalton tells the story of a Quaker prominent in his sect who once went to town to buy a gray waistcoat and purchased instead one of bright red. When he appeared at meeting in this he was promptly tried for heresy and violation of church regulations.

There is an interesting tendency on the part of people who are themselves defective in certain faculties of sensation, to conclude that when other people are wrapt in admiration of something that they cannot perceive, it is because these other people have some mental defect that leads them to enthuse too easily over their sensations. A story is told of a newspaper man who used to insist that all that was said about the beauty of the song of birds was due to the vivid imagination of the writers, for he could find nothing to admire about the songs of birds. He was placed in a room with a number of fine song birds all round him and it proved that he could not hear any of the higher notes at all. It was easy, then, to understand his condemnation of the enthusiasm of others as hysterical and imaginative. Nearly this same thing is true of many quite intelligent people with regard to music. They hear ordinary sounds, as did the newspaper man, very well.

They are tone-deaf however, that is, they are quite unable to hear and appreciate combinations of sounds or even to catch melodious successions of single notes. They cannot recognize one tune from another and often do not know "Yankee Doodle" from the "Doxology," or, at most, know only the most familiar tunes, but they set themselves up very calmly as judges of the intellects of others and conclude that music lovers are really a hysterical set of people who go into ecstasies over certain quite insignificant sensations.

These interesting tendencies are helpful in enabling the physician to understand his patients better. They often serve as texts from which the physician can explain curious things to patients who are p.r.o.ne to draw wrong conclusions from them and often suggestions unfavorable to their health.

These ill.u.s.trations and their discussion serve to make very clear the distinction between illusions, delusions and hallucinations, which are often confounded. Illusions are deceptions of the senses. If a man walking along a country road where he fears the presence of snakes sees in the gathering twilight a piece of rope coiled, he will almost surely mistake it for a snake. This is an illusion produced by the conditions in which the object is seen. If walking along the same road the next day, more timorous than ever as to snakes, he should see in broad daylight the same coil of rope, he might in his fright not stay long enough to decide whether it was a snake or not, and his illusion would continue, though it would partake somewhat of the nature of a delusion due to fright disturbing his judgment. If, in spite of careful examination, however, of it, such as would satisfy any ordinary mind that it was a coil of rope and not a snake, he should still insist in believing that it was a snake, this would be a delusion. There is always a mental element in delusions. If, having seen nothing, he should insist, owing to fright and {774} nervousness or to some other cause, that he sees a snake where there is nothing at all resembling a snake and where evidently whatever is the basis of his idea of the presence of the snake, is within his own mind, then he is suffering from an hallucination.

Illusions may be quite inevitable. Most of the optical illusions continue to appeal to us as truths even when we know that they represent errors of vision. In spite of the fact that we know that the sun and moon are not larger at the horizon than they are at the zenith, by optical illusion we continue to see them of larger size. It is our duty to correct such illusions by information gathered from other sources. To follow an illusion, that is, to give it credit, when we should correct it, is a delusion. To think that because we cannot see red that therefore there is no red, or because we do not hear the sounds of notes of birds that they do not utter any notes, in spite of the fact that we have the testimony of nearly the whole human race to the contrary, is a delusion. When, using the verb in its broadest sense, as "perceive," we seem to see things very differently from the generality of people around us, there is every reason to suspect that there is some specific or individual limitation of our senses which makes us fail to perceive these things as others do. We have to suspect our sources of information then and to correct them by what we can learn from the experience of others. These are important considerations for many of the ideas that patients cherish with regard to themselves and their ills.

Hallucinations are entirely mental. But the phenomena that sometimes appear to be hallucinations may be due to illusions of the senses within the organism. For instance, those who indulge in cocaine often have the feeling of having a veil over the face, or of having run into a cobweb or something of that kind. The presence of the veil or the cobweb on the face is probably not an hallucination, but is due to certain disturbances in the circulation, or perhaps in the nerves themselves, which affect the nerve endings of the face, causing them to tingle in a particular way, and this sensation is translated as coming from without in terms of something that has been felt before.

Some of the appearances of _muscae volitantes_, or of specks before the eyes, or occasionally of wavy lines, are due to disturbances of the circulation within the eyeball which cause corresponding disturbances of the optic nerve, with consequent apparent visions.

When the eyeball is pressed upon, the sensation first produced is that of light and not of pain, because whenever a nerve of special sense is irritated, it produces its own specific sensation in the brain.

The chilly stage in malaria is a typical example of a physical condition having an effect upon sensory nerves that more or less necessarily produces a delusion. The patient is actually at the height of his fever when the chilliness and shivering come on and when he demands a larger amount of covers in order to protect himself from the cold he will often have a temperature of 104 degrees Fahrenheit, or even higher. What has happened is that the little blood vessels at the surface of the body are shut up by the effect of the plasmodium upon the system. Whenever we are cold these little blood vessels shut up in order to protect the blood from being chilled by the external atmosphere. The shutting up of the little blood vessels deprives, for the time being, the terminal nerves in the neighborhood of some of their nourishment. Their response is to set up a tremor or shivering, which will mechanically tend {775} to open the blood vessels so that they may have their nourishment once more. Whenever we have a set of sensations that correspond to this connected set of events, we translate them as feeling cold. The outer air does feel cold to the body because the blood is not flowing through to the surface as it would normally in order to warm it. Hence the chilliness. This is not an hallucination; but an illusion with something of a delusion in it; until we know how things are. Nervousness may set our teeth chattering just as it may cause tremor through our sympathetic nervous system, disturbing the flow of blood through muscles and so disturbing control of them. Vehement emotion, anger, fright, and even those of less violence may cause similar effects. All these phenomena ill.u.s.trate the close relation between mind and body.

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APPENDIX II

RELIGION AND PSYCHOTHERAPY

Religion and psychotherapy have, of late, come to have many relations to each other and many interests in common, at least in the minds of a number of clergymen, and in popular estimation. There is no doubt but that religion can do much to soothe troubled men and women, even when their troubles are entirely physical in nature and origin. It at least lessens the unfavorable effect of worry in exaggerating such pathological processes as are at work. All diseases, functional and organic, are rendered worse by solicitude, while many troublesome symptoms become quite bearable if only the patient does not dwell on them too much but takes them as they come, carefully refraining from emphasizing them by over-attention. That is the very essence of psychotherapy. Religion, in the sense of trust in divine wisdom, can do much to originate and maintain this imperturbed frame of mind.

People who are without religion, that is, without the feeling that somehow all their ills are a part of the great plan of the universe, the mystery of which is insoluble, but the recognition of which is demanded by reason, and who lack the a.s.surance that somehow, in Browning's phrase:

"G.o.d's in His Heaven- All's right with the world!"

-- are more p.r.o.ne to give way to over-anxiety and consequently to make themselves suffer more in all their ills, than is necessary or even likely in the more favorable state of mind of those whose trust in Providence is thorough and efficient.

In recent years there has been in the general population a distinct loss of faith in the great religious truths that are so helpful in engendering a peaceful state of mind in suffering. Many have come, if not to doubt of the Providence of the Creator, at least to feel that we do not know enough about it to place any such supreme dependence on it in the trials of life as would make it a source of relief, or at least consolation, in suffering. This same spirit of doubt has paralyzed faith in the hereafter and in all that trust in it brings, to sufferers, of consolation to come for their ills if these are borne as becomes rational creatures whose suffering has a purpose, though we may not comprehend it. Some people are destined by their physical make-up or by accidental conditions to considerable suffering. There are many ailments that are incurable and are definitely known to be incurable. Some of these entail great suffering of body and even more suffering of mind. Such suffering becomes quite unbearable unless the patient is of a very stoic disposition, or unless the thought of a hereafter in which the sufferings of this life will have a meaning is present to console.

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Great scientists in the midst of all our advance in science--one need but mention here such men as Lord Kelvin, Clerk Maxwell, Johann Muller, Laennec, Pasteur, Claude Bernard, though the number might easily be multiplied--have insisted that the existence of a Creator is absolutely demanded by what we know of the physical universe. "Science demonstrates the existence of a Creator," is Lord Kelvin's expression.

The existence of a Creator implies, also, the existence of laws made by Him, by which His universe is regulated in every detail, nothing being left to chance. Chance is indeed only a term which indicates that we do not know the causes at work. If somehow the Creator's power has been sufficient to bring the manifold things of the universe into existence according to a plan in which there is no such interference with one another as would cause serious disturbance of the universal order around us, then He can be trusted also to care for even the minutest details of creation and of human life.

In the gradual disintegration of the religious sense which has come as a consequence of certain materialistic tendencies in nineteenth century education and science, these religious sources of consolation have been shut off from a great many people. They have come to the feeling of being portions of a machine that moves hopelessly on, somehow, on the old principle, "The mills of the G.o.ds grind slow, but they grind exceeding fine." The sufferings of humanity then, are, for these people, only a portion of a great universe of suffering that is constantly going on but for which they can see no reason and no purpose. Lucretius's lines which make human sufferings the b.u.t.t of the jokes of the G.o.ds who look gleefully on from their Elysian happiness, would represent the feelings of these doubters better than any religious expression. We have come back in this age, when evolution has so much influenced the thought of the time, after the curious cyclic fashion in which human thought repeats itself from era to era, to the att.i.tude of mind of the old Roman poet who almost singly among his contemporaries, had been deeply affected by the same doctrine of evolution. The pessimism he was p.r.o.ne to as to the significance of human life has become once more the fashion.

Such pessimistic thoughts do not come, as a rule, while people are in good health, but they a.s.sert themselves with double emphasis in moments of trial and suffering. Lucretius himself is said to have committed suicide. The result of the diffusion of this materialistic pessimism in our time has been a gradual preparation for a revulsion of feeling in many minds. One manifestation of this reaction has been seen in a form of religion which denies entirely the existence of evil. G.o.d the Creator is good and therefore there can be no evil in His world. Whatever of evil there is, is only due to man's failure to see the entirety of things. Evil is an error of mortal mind--only that and nothing more. In spite of the manifest absurdity of the underlying principle, if people can only be brought to persuade themselves that there is no such thing as evil or suffering, then many of their discomforts disappear, all of their symptoms grow less and a sense of well-being results. It is, indeed, surprising how many even physical ills will be relieved by this state of mind if sincerely accepted. It is the highest possible tribute to psychotherapy and the curative influence of mind over body.

Another phase of this revulsion of feeling has been the inst.i.tution of a church movement that would make sufferers realize once more all the {778} consolations there are in religion. The sufferer is brought to a renewed lively sense of the presence of the Creator in the universe and of His care for His creatures. The great purpose of suffering in making people better and stripping them of their meanness and selfishness is brought out. Anyone who has ever had called to his attention the difference between two brothers, one of whom has been chastened by suffering above which he has risen by character development, and another who has enjoyed good health and prosperity all his life, will realize how much of good suffering means in the world. Pain is not in itself an evil, but a warning, and most of the trials of life can rather readily be shown to partake of this character. A man who can be made to submit himself, then, to the will of the Creator and be persuaded to acknowledge that somehow we must try to work out our part in the great scheme of things behind which the Creator stands, is somewhat like the soldier ready even when tired and worn out, to go in on a forlorn hope, because he has confidence that he is executing a part of the plan of his general for his country's welfare, though he does not know how, and he is quite well aware that it is going to cost him much in pain and suffering, and perhaps his life.

There is no doubt that an abiding sense of religion does much for people in the midst of their ailments and, above all, keeps them from developing those symptoms due to nervous worry and solicitude which so often are more annoying to the patient than the actual sufferings he or she may have to bear. While religion is often said to predispose to certain mental troubles, it is now well appreciated by psychiatrists that it is not religion that has the tendency to disturb the mind, but a disequilibrated mind has a tendency to exaggerate out of all reason its interests in anything that it takes up seriously. Whether the object of the attention be business, or pleasure, or s.e.xuality, or religion, the unbalanced mind pays too much attention to it, becomes too exclusively occupied with it, and this over-indulgence helps to form a vicious circle of unfavorable influence. While many people in their insanity, then, show exaggerated interest in religion, this is only like other exaggerated interests of the disequilibrated, and religion itself is not the cause but only a coincidence in the matter.

Clouston, in his book on "Unsoundness of Mind" (Methuen, London, 1911), put this very well when he said, "It is true that religion, touching as it does, in the most intense way the emotional nature, and the spiritual instincts of mankind, sometimes appears to cause and is often mixed up with insanity. But in nearly all such cases the brain of the individual was originally unstable, specially emotional, over-sensitive, hyperconscientious, and often somewhat weak in the intellectual and inhibitory faculties and, if looked for, other causes will usually be found." He had said just before, "To talk of 'religious insanity' as if it were a definite and definable form is in my judgment a mistake."

On the contrary, there is now a growing conviction that a deep religious feeling, a sense of dependence on and trust in the Almighty, will do more than anything else to keep people from those neurotic manifestations which so often are seen in our day and are growing more and more frequent as life becomes more strenuous and more attention is paid to the material side of things, to the exclusion of the spiritual. How true this is may be judged from expressions that have been used in recent years by well-known specialists in {779} nervous diseases and in psychology. These have included men who were often not believers in religion themselves but who recognized its influence for good for others. Such expressions are to be found in the writings of men of every nationality. Not infrequently, in spite of their own religious affiliation, they acknowledge what a profound influence certain forms of religion have over people. These testimonies have been multiplying in our medical literature in recent years, because apparently physicians have come to appreciate much better by contrast the influence for good of religion over some of their patients, since so many of the sufferers from nervous diseases they see have not this source of consolation to recur to.

In America we have a number of such testimonies. In his "Self Help for Nervous Women" Dr. John K. Mitch.e.l.l of Philadelphia, who may be taken to represent in this matter the Philadelphia School of Neurologists, to which his father has lent such distinction, said: