Since in this vague interpretation of bodily sensation the actual impression is obscured, and not taken up as an integral part into the percept, it is evident that we cannot, strictly speaking, call the process an imitation of an act of perception, that is to say, an illusion. And since, moreover, the visual image by which the sensation is thus displaced appears as a present object, it would, of course, be allowable to speak of this as an hallucination. This subst.i.tution of a more or less a.n.a.logous visual image for that appropriate to the sensation forms, indeed, a transition from dream-illusion, properly so called, to dream-hallucination.
_Dream-Hallucinations._
On the physical side, these hallucinations answer to cerebral excitations which are central or automatic, not depending on movements transmitted from the periphery of the nervous system. Of these stimulations some appear to be direct, and due to unknown influences exerted by the state of nutrition of the cerebral elements, or the action of the contents of the blood-vessels on these elements.
_Effects of Direct Central Stimulation._
That such action does prompt a large number of dream-images may be regarded as fairly certain. First of all, it seems impossible to account for all the images of dream-fancy as secondary phenomena connected by links of a.s.sociation with the foregoing cla.s.ses of sensation. However fine and invisible many of the threads which hold together our ideas may be, they will hardly explain the profusion and picturesque variety of dream-imagery. Secondly, we are able in certain cases to infer with a fair amount of certainty that a dream-image is due to such central stimulation. The common occurrence that we dream of the more stirring events, the anxieties and enjoyments of the preceding day, appears to show that when the cerebral elements are predisposed to a certain kind of activity, as they are after having been engaged for some time in this particular work, they are liable to be excited by some stimulus brought directly to bear on them during sleep. And if this is so, it is not improbable that many of the apparently forgotten images of persons and places which return with such vividness in dreams are excited by a mode of stimulation which is for the greater part confined to sleep. I say "for the greater part," because even in our indolent, listless moments of waking existence such seemingly forgotten ideas sometimes return as though by a spontaneous movement of their own and by no discoverable play of a.s.sociation.
It may be well to add that this immediate revival of impressions previously received by the brain includes not only the actual perceptions of waking life, but also the ideas derived from others, the ideal fancies supplied by works of fiction, and even the images which our unaided waking fancy is wont to shape for itself. Our daily conjectures as to the future, the communications to us by others of their thoughts, hopes, and fears,--these give rise to numberless vague fugitive images, any one of which may become distinctly revived in sleep.[92] This throws light on the curious fact that we often dream of experiences and events quite unlike those of our individual life. Thus, for example, the common construction by the dream-fancy of the experience of flight in mid-air, and the creation of those weird forms which the terror of a nightmare is wont to bring in its train, seem to point to the past action of waking fancy. To imagine one"s self flying when looking at a bird is probably a common action with all persons, at least in their earlier years, and images of preternaturally horrible beings are apt to be supplied to most of us some time during life by nurses or by books.
_Indirect Central Stimulation._
Besides these direct central stimulations, there are others which, in contradistinction, may be called indirect, depending on some previous excitation. These are, no doubt, the conditions of a very large number of our dream-images. There must, of course, be some primary cerebral excitation, whether that of a present peripheral stimulation, or that which has been termed central and spontaneous; but when once this first link of the imaginative chain is supplied, other links may be added in large numbers through the operation of the forces of a.s.sociation. One may, indeed, safely say that the large proportion of the contents of every dream arise in this way.
The very simplest type of dream excited by a present sensation contains these elements. To take an example, I once dreamt, as a consequence of the loud barking of a dog, that a dog approached me when lying down, and began to lick my face. Here the play of the a.s.sociative forces was apparent: a mere sensation of sound called up the appropriate visual image, this again the representation of a characteristic action, and so on. So it is with the dreams whose first impulse is some central or spontaneous excitation. A momentary sight of a face or even the mention of a name during the preceding day may give the start to dream-activity; but all subsequent members of the series of images owe their revival to a tension, so to speak, in the fine threads which bind together, in so complicated a way, our impressions and ideas.
Among the psychic accompaniments of these central excitations visual images, as already hinted, fill the most conspicuous place. Even auditory images, though by no means absent, are much less numerous than visual. Indeed, when there are the conditions for the former, it sometimes happens that the auditory effect transforms itself into a visual effect. An ill.u.s.tration of this occurred in my own experience.
Trying to fall asleep by means of the well-known device of counting, I suddenly found myself losing my hold on the faint auditory effects, my imagination transforming them into a visual spectacle, under the form of a path of light stretching away from me, in which the numbers appeared under the grotesque form of visible objects, tumbling along in glorious confusion.
Next to these visual phantasms, certain motor hallucinations seem to be most prominent in dreams. By a motor hallucination, I mean the illusion that we are actually moving when there is no peripheral excitation of the motor organ. Just as the centres concerned in pa.s.sive sensation are susceptible of central stimulation, so are the centres concerned in muscular sensation. A mere impulse in the centres of motor innervation (if we a.s.sume these to be the central seat of the muscular feelings) may suffice to give rise to a complete representation of a fully executed movement. And thus in our sleep we seem to walk, ride, float, or fly.
The most common form of motor hallucination is probably the vocal. In the social encounters which make up so much of our sleep-experience, we are wont to be very talkative. Now, perhaps, we find ourselves zealously advocating some cause, now very fierce in denunciation, now very amusing in witty repartee, and so on. This imagination of ourselves as speaking, as distinguished from that of hearing others talking, must, it is clear, involve the excitation of the structures engaged in the production of the muscular feelings which accompany vocal action, as much as, if not more than, the auditory centres. And the frequency of this kind of dream-experience may be explained, like that of visual imagery, by the habits of waking life. The speech impulse is one of the most deeply rooted of all our impulses, and one which has been most frequently exercised in waking life.
_Combination of Dream-Elements._
It is commonly said that dreams are a grotesque dissolution of all order, a very chaos and whirl of images without any discoverable connection. On the other hand, a few writers claim for the mind in sleep a power of arranging and grouping its incongruous elements in definite and even life-like pictures. Each of these views is correct within certain limits; that is to say, there are dreams in which the strangest disorder seems to prevail, and others in which one detects the action of a central control. Yet, speaking generally, sequences of dream-images will be found to be determined by certain circ.u.mstances and laws, and so far not to be haphazard or wholly chaotic. We have now to inquire into the laws of these successions; and, first of all, we may ask how far the known laws of a.s.sociation, together with the peculiar conditions of the sleeping state, are able to account for the various modes of dream-combination. We have already regarded mental a.s.sociation as furnishing a large additional store of dream-imagery; we have now to consider it as explaining the sequences and concatenations of our dream-elements.
_Incoherence of Dreams._
First of all, then, let us look at the chaotic and apparently lawless side of dreaming, and see whether any clue is discoverable to the centre of this labyrinth. In the case of all the less elaborately ordered dreams, in which sights and sounds appear to succeed one another in the wildest dance (which cla.s.s of dreams probably belongs to the deeper stages of sleep), the mind may with certainty be regarded as purely pa.s.sive, and the mode of sequence may be referred to the action of a.s.sociation complicated by the ever-recurring introduction of new initial impulses, both peripheral and central. These are the dreams in which we are conscious of being perfectly pa.s.sive, either as spectators of a strange pageant, or as borne away by some apparently extraneous force through a series of the most diverse experiences. The flux of images in these dreams is very much the same as that in certain waking conditions, in which we relax attention, both external and internal, and yield ourselves wholly to the spontaneous play of memory and fancy.
It is plain at a glance that the simultaneous concurrence of wholly disconnected initial impulses will serve to impress a measure of disconnectedness on our dream-images. From widely remote parts of the organism there come impressions which excite each its peculiar visual or other image according as its local origin or its emotional tone is the more distinctly present to consciousness. Now it is a subjective ocular sensation suggesting a bouquet of lovely flowers, and close on its heels comes an impression from the organs of digestion suggesting all manner of obstacles, and so our dream-fancy plunges from a vision of flowers to one of dreadful demons.
Let us now look at the way in which the laws of a.s.sociation working on the incongruous elements thus cast up into our dream-consciousness, will serve to give a yet greater appearance of disorder and confusion to our dream-combinations. According to these laws, any idea may, under certain circ.u.mstances, call up another, if the corresponding impressions have only once occurred together, or if the ideas have any degree of resemblance, or, finally, if only they stand in marked contrast with one another. Any accidental coincidence of events, such as meeting a person at a particular foreign resort, and any insignificant resemblance between objects, sounds, etc., may thus supply a path, so to speak, from fact to dream-fancy.
In our waking states these innumerable paths of a.s.sociation are practically closed by the supreme energy of the coherent groups of impressions furnished us from the world without through our organs of sense, and also by the volitional control of internal thought in obedience to the pressure of practical needs and desires. In dream-life both of these influences are withdrawn, so that delicate threads of a.s.sociation, which have no chance of exerting their pull, so to speak, in our waking states, now make known their hidden force. Little wonder, then, that the filaments which bind together these dream-successions should escape detection, since even in our waking thought we so often fail to see the connection which makes us pa.s.s in recollection from a name to a visible scene or perhaps to an emotional vibration.
It is worth noting that the origin of an a.s.sociation is often to be looked for in one of those momentary half-conscious acts of waking imagination to which reference has already been made. A friend, for example, has been speaking to us of some common acquaintance, remarking on his poor health. The language calls up, vaguely, a visual representation of the person sinking in health and dying. An a.s.sociation will thus be formed between this person and the idea of death. A night or two after, the image of this person somehow recurs to our dream-fancy, and we straightway dream that we are looking at his corpse, watching his funeral, and so on. The links of the chain which holds together these dream-images were really forged, in part, in our waking hours, though the process was so rapid as to escape our attention. It may be added, that in many cases where a juxtaposition of dream-images seems to have no basis in waking life, careful reflection will occasionally bring to light some actual conjunction of impressions so momentary as to have faded from our recollection.
We must remember, further, how great an apparent disorder will invade our imaginative dream-life when the binding force of resemblance has unchecked play. In waking thought we have to connect things according to their essential resemblances, cla.s.sifying objects and events for purposes of knowledge or action, according to their widest or their most important points of similarity. In sleep, on the contrary, the slightest touch of resemblance may engage the mind and affect the direction of fancy. In a sense we may be said, when dreaming, to discover mental affinities between impressions and feelings, including those subtle links of emotional a.n.a.logy of which I have already spoken. This effect is well ill.u.s.trated in a dream recorded by M. Maury, in which he pa.s.sed from one set of images to another through some similarity of names, as that between _corps_ and _cor_. Such a movement of fancy would, of course, be prevented in full waking consciousness by a predominant attention to the meaning of the sounds.
It will be possible, I think, after a habit of a.n.a.lyzing one"s dreams in the light of preceding experience has been formed, to discover in a good proportion of cases some hidden force of a.s.sociation which draws together the seemingly fortuitous concourse of our dream-atoms. That we should expect to do so in every case is unreasonable, since, owing to the numberless fine ramifications which belong to our familiar images, many of the paths of a.s.sociation followed by our dream-fancy cannot be afterwards retraced.
To ill.u.s.trate the odd way in which our images get tumbled together through the action of occult a.s.sociation forces, I will record a dream of my own. I fancied I was at the house of a distinguished literary acquaintance, at her usual reception hour. I expected the friends I was in the habit of meeting there. Instead of this, I saw a number of commonly dressed people having tea. My hostess came up and apologized for having asked me into this room. It was, she said, a tea-party which she prepared for poor people at sixpence a head. After puzzling over this dream, I came to the conclusion that the missing link was a verbal one. A lady who is a connection of my friend, and bears the same name, a.s.sists her sister in a large kind of benevolent scheme. I may add that I had not, so far as I could recollect, had occasion very recently to think of this benevolent friend, but I had been thinking of my literary friend in connection with her antic.i.p.ated return to town.
In thus seeking to trace, amid the superficial chaos of dream-fancy, its hidden connections, I make no pretence to explain why in any given case these particular paths of a.s.sociation should be followed, and more particularly why a slender thread of a.s.sociation should exert a pull where a stronger cord fails to do so. To account for this, it would be necessary to call in the physiological hypothesis that among the nervous elements connected with a particular element, _a_, already excited, some, as _m_ and _n_, are at the moment, owing to the state of their nutrition or their surrounding influences, more powerfully predisposed to activity than other elements, as _b_ and _c_.
The subject of a.s.sociation naturally conducts us to the second great problem in the theory of dreams--the explanation of the order in which the various images group themselves in all our more elaborate dreams.
_Coherence of Dreams._
A fully developed dream is a complex of many distinct illusory sense-presentations: in this respect it differs from the illusions of normal waking life, which are for the most part single and isolated. And this complex of quasi-presentations appears somehow or other to fall together into one whole scene or series of events, which, though it may be very incongruous and absurdly impossible from a waking point of view, nevertheless makes a single object for the dreamer"s internal vision, and has a certain degree of artistic unity. This plastic force, which selects and binds together our unconnected dream-images, has frequently been referred to as a mysterious spiritual faculty, under the name of "creative fancy." Thus Cudworth remarks, in his _Treatise concerning Eternal and Immutable Morality_: "That dreams are many times begotten by the phantastical power of the soul itself ... is evident from the orderly connection and coherence of imaginations which many times are continued in a long chain or series." One may find a good deal of mystical writing on the nature and activity of this faculty, especially in German literature. The explanation of this element of organic unity in dreams is, it may be safely said, the crux in the science of dreams.
That the laws of psychology help us to understand the sequences of dream-images, we have seen. What we have now to ask is whether these laws throw any light on the orderly grouping of the elements so brought up in consciousness in the form of a connected experience.
It is to be remarked at the outset that a singular kind of unity is sometimes given to our dream-combinations by a total or partial coalescence of different images. The conditions of such coalescence have been referred to already.[93] Simultaneous impressions or images will always tend to coalesce with a force which varies directly as the degree of their similarity. Sometimes this coalescence is instantaneous and not made known to consciousness. Thus, Radestock suggests that if the mind of the sleeper is simultaneously invaded by an unpleasant sensation arising out of some disturbance of the functions of the skin, and a subjective visual sensation, the resulting mental image may be a combination of the two, under the form of a caterpillar creeping over the bodily surface. And the coalescence may even be prepared by sub-conscious operations of waking imagination. Thus, for example, I once spoke about the cheapness of hares to a member of my family, who somewhat grimly suggested that they were London cats. I did not dwell on the idea, but the following night I dreamt that I saw a big hybrid creature, half hare, half cat, sniffing about a cottage. As it stood on its hind legs and took a piece of food from a window-ledge, I became sure that it was a cat. Here it is plain that the cynical observation of my relative had, at the moment, partially excited an image of this feline hare. In some dreams, again, we may become aware of the process of coalescence, as when persons who at one moment were seen to be distinct appear to our dream-fancy to run together in some third person.
A very similar kind of unification takes place between sequent images under the form of transformation. When two images follow one another closely, and have anything in common, they readily a.s.sume the form of a trans.m.u.tation. There is a sort of overlapping of the mental images, and so an appearance of continuity produced in some respects a.n.a.logous to that which arises in the wheel-of-life (thaumatrope) cla.s.s of sense-illusions. This would seem to account for the odd transformations of personality which not unfrequently occur in dreams, in which a person appears, by a kind of metempsychosis, to transfer his physical ego to another, and in which the dreamer"s own bodily phantom plays similar freaks. And the same principle probably explains those dissolving-view effects which are so familiar an accompaniment of dream-scenery.[94]
But pa.s.sing from this exceptional kind of unity in dreams, let us inquire how the heterogeneous elements of our dream-fancy become ordered and arranged when they preserve their separate existence. If we look closely at the structure of our more finished dreams, we find that the appearance of harmony, connectedness, or order, may be given in one of two ways. There may, first of all, be a subjective harmony, the various images being held together by an emotional thread. Or there may, secondly, be an objective harmony, the parts of the dream, though answering to no particular experiences of waking life, bearing a certain resemblance to our habitual modes of experience. Let us inquire into the way in which each kind of order is brought about.
_Lyrical Element in Dreams._
The only unity that belongs to many of our dreams is a subjective emotional unity. This is the basis of harmony in lyrical poetry, where the succession of images turns mainly on their emotional colouring.
Thus, the images that float before the mind of the Poet Laureate, in his _In Memoriam_, clearly have their link of connection in their common emotional tone, rather than in any logical continuity. Dreaming has been likened to poetic composition, and certainly many of our dreams are built upon a groundwork of lyrical feeling. They might be marked off, perhaps, as our lyrical dreams.
The way in which this emotional force acts in these cases has already been hinted at. We have seen that the a.n.a.logy of feeling is a common link between dream-images. Now, if any shade of feeling becomes fixed and dominant in the mind, it will tend to control all the images of the time, allowing certain congruous ones to enter, and excluding others.[95] If, for example, a feeling of distress occupies the mind, distressing images will have the advantage in the struggle for existence which goes on in the world of mind as well as in that of matter. We may say that attention, which is here wholly a pa.s.sive process, is controlled by the emotion of the time, and bent in the direction of congruent or harmonious images.
Now, a ground-tone of feeling of a certain complexion, answering to the sum of sensations arising in connection with the different organic processes of the time, is a very frequent foundation of our dream-structure. So frequent is it, indeed, that one might almost say there is no dream in which it is not one great determining factor. The a.n.a.lysis of a very large number of dreams has convinced me that traces of this influence are discoverable in a great majority.
I will give a simple ill.u.s.tration of this lyrical type of dream. A little girl of about four years and three-quarters went with her parents to Switzerland. On their way she was taken to the cathedral at Strasburg, and saw the celebrated clock strike, and the figures of the Apostles come out, etc. In Switzerland she stayed at Gimmelwald, near Murren, opposite a fine ma.s.s of snowy mountains. One morning she told her father that she had had "such a lovely dream." She fancied she was on the snow-peaks with her nurse, and walked on to the sky. There came out of the sky "such beautiful things," just like the figures of the clock. This vision of celestial things was clearly due to the fact that both the clock and the snow-peaks touching the blue sky had powerfully excited her imagination, filling her with much the same kind of emotion, namely, wonder, admiration, and longing to reach an inaccessible height.
Our feelings commonly have a gradual rise and fall, and the organic sensations which so often const.i.tute the emotional basis of our lyrical dreams generally have stages of increasing intensity. Moreover, such a persistent ground-feeling becomes reinforced by the images which it sustains in consciousness. Hence a certain _crescendo_ character in our emotional dreams, or a gradual rise to some culminating point or climax.
This phase of dream can be ill.u.s.trated from the experience of the same little girl. When just five years old, she was staying at Hampstead, near a church which struck the hours somewhat loudly. One morning she related the following dream to her father (I use her own language). The biggest bells in the world were ringing; when this was over the earth and houses began to tumble to pieces; all the seas, rivers, and ponds flowed together, and covered all the land with black water, as deep as in the sea where the ships sail; people were drowned; she herself flew above the water, rising and falling, fearing to fall in; she then saw her mamma drowned, and at last flew home to tell her papa. The gradual increase of alarm and distress expressed in this dream, having its probable cause in the c.u.mulative effect of the disturbing sound of the church bells, must be patent to all.
The following rather comical dream ill.u.s.trates quite as clearly the growth of a feeling of irritation and vexation, probably connected with the development of some slightly discomposing organic sensation. I dreamt I was unexpectedly called on to lecture to a cla.s.s of young women, on Herder. I began hesitatingly, with some vague generalities about the Augustan age of German literature, referring to the three well-known names of Lessing, Schiller, and Goethe. Immediately my sister, who suddenly appeared in the cla.s.s, took me up, and said she thought there was a fourth distinguished name belonging to this period.
I was annoyed at the interruption, but said, with a feeling of triumph, "I suppose you mean Wieland?" and then appealed to the cla.s.s whether there were not twenty persons who knew the names I had mentioned to one who knew Wieland"s name. Then the cla.s.s became generally disorderly. My feeling of embarra.s.sment gained in depth. Finally, as a climax, several quite young girls, about ten years and less, came and joined the cla.s.s.
The dream broke off abruptly as I was in the act of taking these children to the wife of an old college tutor, to protest against their admission.
It is worth noting, perhaps, that in this evolution of feeling in dreaming the quality of the emotion may vary within certain limits. One shade of feeling may be followed by another and kindred shade, so that the whole dream still preserves a degree, though a less obvious degree, of emotional unity. Thus, for example, a lady friend of mine once dreamt that she was in church, listening to a well-known novelist of the more earnest sort, preaching. A wounded soldier was brought in to be shot, because he was mortally wounded, and had distinguished himself by his bravery. He was then shot, but not killed, and, rolling over in agony, exclaimed, "How long!" The development of an extreme emotion of horror out of the vague feeling of awe which is a.s.sociated with a church, gives a curious interest to this dream.
_Verisimilitude in Dreams._
I must not dwell longer on this emotional basis of dreams, but pa.s.s to the consideration of the second and objective kind of unity which characterizes many of our more elaborate dream-performances. In spite of all that is fitful and grotesque in dream-combination, it still preserves a distant resemblance to our actual experience. Though no dream reproduces a particular incident or chain of incidents in this experience, though the dream-fancy invariably transforms the particular objects, relations, and events of waking life, it still makes the order of our daily experience its prototype. It fashions its imaginary world on the model of the real. Thus, objects group themselves in s.p.a.ce, and act on one another conformably to these perceived s.p.a.ce-relations; events succeed one another in time, and are often seen to be connected; men act from more or less intelligible motives, and so on. In this way, though the dream-fancy sets at nought the particular relations of our experience, it respects the general and constant relations. How are we to account for this?
It is said by certain philosophers that this superposition of the relations of s.p.a.ce, time, causation, etc., on the products of our dream-fancy is due to the fact that all experience arises by a synthesis of mental forms with the chaotic matter of sense-impressions. These philosophers allow, however, that all particular connections are determined by experience. Accordingly, what we have to do here is to inquire how far this scientific method of explaining mental connections by facts of experience will carry us. In other words, we have to ask what light can be thrown on these tendencies of dream-imagination by ascertained psychological laws, and more particularly by what are known as the laws of a.s.sociation.
These laws tell us that of two mental phenomena which occur together, each will tend to recall the other whenever it happens to be revived. On the physiological side, this means that any two parts of the nervous structures which have acted together become in some way connected, so that when one part begins to work the other will tend to work also. But it is highly probable that a particular structure acts in a great many different ways. Thus, it may be stimulated by unlike modes of stimuli, or it may enter into very various connections with other structures.
What will follow from this? One consequence would appear to be that there will be developed an organic connection between the two structures, of such a kind that whenever one is excited the other will be disposed to act somehow and anyhow, even when there is nothing in the present mode of activity of the first structure to determine the second to act in some one definite way, in other words, when this mode of activity is, roughly speaking, novel.
Let me ill.u.s.trate this effect in one of the simplest cases, that of the visual organ. If, when walking out on a dark night, a few points in my retina are suddenly stimulated by rays of light, and I recognize some luminous object in a corresponding direction, I am prepared to see something above and below, to the right and to the left of this object.