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Chapter 17

The Power Of Phantasy In Dreams

355. One of the extraordinary phenomena associated with phantasy is its extremely active presence in sleep when the whole body is weak, and the exterior senses are, as it were, shut down. I do not want to attempt an explanation of this fact, however, but offer my own simple way of conceiving it, which may perhaps be of assistance to philosophers wanting to develop a better understanding of it, and more in conformity with all the facts that further observation may bring to light.

I imagine the whole nervous system as possessing two extremities, one which terminates principally in the cutaneous organ, and the other in the brain and in the spinal cord (cf. 351). These nerves, organs of feeling, are then moved by two kinds of stimuli: external stimuli, foreign to our body or rather consisting entirely of matter foreign to the organs of sensation; and internal stimuli, that is, the motor force of the soul.

Let us now suppose that the nerve filaments have two periodic movements. In the first movement, the nerve filament extends very slowly from the inside to the outside, and moves the tiny nerve endings forward - rather like the outward movement of the snail's antennae. This slow, but continual outward movement of the nerve endings must however have an extreme term in which it comes to rest. When it has reached this term and attained the maximum activity possible to external feeling, the tiny nerve ending cannot remain long under extreme tension without relaxing. When this relaxation of the outwardly poised nerve has reached a certain point it causes contrary movement in the nerve itself. The nerve retreats inwardly, and draws in its wake all the tiny endings it had expanded and pushed outward. This reverse movement continues until the nerve has withdrawn as far as possible to the opposite extreme, and the interior extremities or endings have expanded and pushed outward as the exterior ends did. The nerve remains at rest only a short time before it resumes its natural movement outwards. These two very slow, periodic movements alternate unceasingly in human life .

356. It must be clear to everyone that such a supposition about two unfeelable movements of the nervous system would explain periods of sleep and wakefulness. We would be awake when the nervous system, active and alert, is drawn by its own natural inclination towards sensation, is prepared to encounter external stimuli, and is open to outward expansion, which would permit it to receive impressions easily. After prolonged enjoyment of this state the nervous system, tired by its vital action and consequent straining forward, would insensibly retreat and turn back on itself. Action would cease, and the nervous system would concentrate itself in rest while the extremities of the nervous protuberances closed in on themselves and no longer accepted exterior impressions - as happens in sleep. To help this periodic movement, the Creator decreed in his infinite wisdom that day should be followed by night, when the stimuli of light and heat cease and even the impact of the air on life lessens because there is no light to draw oxygen from plants (oxygen is perhaps the principal stimulant of life).

357. What we have said also furnishes a very easy way of conceiving the powerful increase of phantasy during the night and in sleep. In the first place, by removing many stimuli from our exterior sensitivity, darkness must render our phantasy more active, in accordance with the law stating: `The soul's power is more forceful when it is concentrated in a lesser number of faculties.' When people lose a sense - blind persons, for example - their remaining faculties become more acute.

However, although this would help in some way to explain the greater power of the imagination during the hours of darkness, it does not explain the extreme power present in dreams. But the supposition from which we start does lead, I think, to a very clear explanation. As the nerves are withdrawn from exterior stimuli with the onset of sleep, they gradually retreat inwardly and come to expand and extend their internal extremities in the brain or the spinal cord. Here they are more apt to receive the action and movements of internal stimuli, which may be either the bodily fluids or solids, or the power of the soul itself which, seconding the first movements of these fluids and solids, orders the nerves to move, and effectively moves them with sufficient force to produce images. And I think it likely that the movement caused by the soul must begin in the internal extremities which are at the heart of our supposition.(165)

358. My way of conceiving the imagination and its phenomena depends, of course, upon supposition and conjecture. Nevertheless, it cannot be denied that it has some basis in certain facts that give it a degree of probability. One fact is that the soul undoubtedly contributes its own activity when it receives feelings. Moreover, it contributes especially by assisting the nerves to provide the tendency and opening needed to receive the impression in a better way. The soul applies and adapts the nerves to the object and joins it, as it were, in undertaking the operation more effectively. For example, we stare when we want to see something clearly; or we look more intently when light is dim; or screw up our eyes when we want to see something tiny, and become

Something similar occurs when we strain to hear faint sounds or voices, or the words of an eloquent speaker; or when we want to taste or smell something.(167) The same thing occurs even in our touch. I have no doubt that when we want to feel subtle differences in things we touch, we not only accommodate the hand to all the surfaces of the object, but also extend and expand the nerve protuberances in which the impression is brought together. Blind people soon become expert in this.

These facts seem to support our belief that the soul, avid for sensation, moves to meet the objects providing sensation as soon they are even slightly perceived. It pushes the tiny nerves towards the objects, prompting the nerves to receive the objects like flowers opening to receive light, air and dew. The same desire and inclination for feeling, and for renewed, vivid feeling, turns the child's eyes towards every variation of light, and in general explains all infantile movements whose sole object seems the perpetual attainment of vivacious, varied sensations.

359. Let us make another conjecture. I think it highly likely that the alternating movement of the nerves, which I have posited in the animal, begins at birth when the animal comes in contact with light and air. As long as the subject is a foetus, it would seem to lack this movement. Its nerve state prior to birth may be that of sleep or constant stupor from which it is aroused by the new external stimuli of air and light that provoke nerve movement and breathing. The baby's need for a great deal of sleep could be another proof of the gradually awakening to which the animal has to accustom itself little by little as it activates its nerves in the way suggested.(168)

360. Many other facts fit in well with our conjecture about the existence of this alternating movement. For example, the soul's tendency to `go out' to sensation would account for our waking at the sound of some unusual noise, or when powerful impressions affect us as we sleep.(169)

361. Another fact harmonising with our supposition is that an over-strong impression, especially if applied to the whole body, causes sleep rather than awakens. Excessive cold,(170) pain and tiredness all make us fall asleep. This phenomenon can easily be explained if we grant that being awake consists in nerve extension towards the attraction of sensations, which always delight the soul if they are not excessive. If they are excessive, the nerve retreats from them into itself for two reasons. First, the liveliness of the stimulus has accelerated the movement of the nerve so that it reaches its extreme development too soon, and begins to turn back. Second, the action of the nerve in moving instinctively away from its disturbed state appears to be similar to the action of the aperture of the iris when the eye is struck by excessive light.

362. Our supposition would also help to explain partial sleep, to which a part, not all of the body is subject. Generally speaking, the same would be true of all diseases associated with sleep. These must depend upon a change in the movement of the nerves, alternating like a weaver's bobbin.

363. Another exceptional fact which seems to support my supposition is that brain compression precedes sleep in an animal. Haller's experiments on brain compression in animals are well-known, but sleep followed upon brain compression has also been signalled in human beings. On opening the cranium of sleepy people, Bonnet, Vallins, Fantoni. Wepfer, Bautin and others noted tumours within the skull that were exerting pressure on the encephalic mass; Willis found that meninges were inflamed and covered with blood in several patients; others found the brain ventricles under pressure from serum. Planque testifies to sleep caused by wounds penetrating the brain. Atkins explains frequent lethargy in hot climates by higher than average expansion of blood in the brain, and its consequent capacity for exerting pressure. It is clear that our supposition about movement in the nerves would harmonise exactly with these observations. If the entire nerve system retreated towards the brain, it would inevitably swell and produce the kind of pressure we are considering.(171) On the other hand, while there is no evidence to show that this compression comes about through the flow of blood to the head, there is evidence that sleep is connected with causes diverting the blood from the head and increasing it elsewhere, as we can see in the case of poultices or when feet are immersed in hot water.

364. Another fact meriting careful consideration could also be weight absorption, which is greater during sleep than in periods of wakefulness. Other kinds of absorption also increase during sleep. This seems to harmonise particularly well with our supposition about the retractory movement of the nerves.(172)

365. A difficulty arises when we observe apparent extreme wakefulness combined with very active phantasy and drowsy external feeling in people suffering from mental alienation. The wakefulness is, of course, due to extraordinary arousal of the nervous system which allows no rest to the nerves and the brain. But in this case, retraction of the nerves will be equally violent and irregular. It will not be the characteristic, natural slowing down suitable for producing phenomena accompanying sleep. People suffering from insanity can in great part be compared with somnambulists.

Notes

(165) An excellent field for observation and research would be provided by the electrical condition of the two supposed nerve extremities. Matteucci's experiments on torpedo fish have provided a fine basis for such work. According to him, he has proved: 1. that the electricity producing the charge in the torpedo fish comes from the fourth lobe of the brain which is the source of the nerves that go to the electric organs; 2. that if these nerves are cut or tied, all electrical effect ceases; 3. that ligaturing the leg of a frog results in suspension of the current proper to the animal; 4. that on the contrary ligaturing the nerves does not suspend the passage of simple electro-chemical current either in the torpedo fish or in the frog. This shows that animal electricity has its own laws which do not coincide with those of ordinary electricity.

- Professor Stefano Mariannini maintains that his experiments on frogs lead to the following important conclusions: `Electric fluid, when permeating a nerve in the direction of the nerve's movement, produces a muscular contraction, but when it ceases to flow, a sensation. When the fluid permeates the nerve in the opposite direction of the nerve's movement, it produces a sensation, but when it ceases to flow, a contraction' (in a Memorandum presented to the Academy of Rovereto as early as 1827 and printed the following year by Alvisopoli at Venice under the title: Memoria sopra la scossa che provano gli animali nel momento che cessano di fare arco di communicazione fra i poli di un elettromotore, e sopra qualche altro fenomeno fisiologico dell'elettricità). This shows that sensation corresponds with determined movements of the nervous system, not with every movement. As a result, it also shows that 1. it is possible for certain parts of the body to seem void of sense capacity when stimulated, simply because we do not succeed in causing those particular alterations which alone accompany sensation; 2. the soul can indeed use sensory nerves for movement, without necessarily exciting vivid sensations when moving these nerves.

(166) `Looking' means acting upon the nerve of the eye so as to present it suitably to the object we want to see. Physiologists, therefore, classify sensation as active and passive. But it would be more accurate to say that every sensation is passive, although the soul contributes with a given degree of activity to the production of this passivity. Languages indicate this activity of the soul with special words. For instance, when the activity is considerable we do not say that we see, but that we look; not that we hear, but that we listen. Such differences are found in all languages. Latin, for example, as videre and aspicere, audire and auscultare, and so on.

(167) Haller maintains that when we taste something, the nerve protuberances rise visibly.

(168) Buffon and other naturalists think that the foetus in the womb is asleep almost continually.

(169) Verduc and others have observed a phenomenon that merits further consideration. A sound or other impression on the skin that serves to wake us forcefully is felt more strongly at that moment than when we are awake. Does this happen because of the speed with which the nerve-head hurries to accept the impression? Or is the vividness of the sensation to be attributed mainly to this rapidity rather than to the nerve fibre itself? Is the rapidity of the nerve movement the effect of a greater degree of activity contributed by the soul to the production of the sensation?

(170) It would be frivolous to object that cold is not a stimulus. For sense, any cause of change is a stimulus. A clock or mill stopping rouses a person from sleep as effectively as a loud noise. When we speak of `sense', it is the soul rather than the body which receives the stimulus.

(171) A. C. Lorry differs from Haller in attributing sleep to compression of the cerebellum, not the brain. D. Hartley has recourse to compression in explaining drowsiness in children, which he attributes to overloading of the head.

(172) Hippocrates' dictum: `Movements in sleep have an internal direction' is quoted in a book I have before me but, lacking the works of Hippocrates at this moment, I cannot verify the meaning he gives to these words.