four forms, which are also utilised for the division of dreams:—
I. External (objective) sensory stimuli.
II. Internal (subjective) sensory stimuli.
III. Internal (organic) physical excitations.
IV. Purely psychical exciting sources.
I. _The External Sensory Stimuli._—The younger Strümpell, son of the
philosopher whose writings on the subject have already more than once
served us as a guide in the problem of dreams, has, as is well known,
reported his observations on a patient who was afflicted with general
anæsthesia of the skin and with paralysis of several of the higher
sensory organs. This man merged into sleep when his few remaining
sensory paths from the outer world were shut off. When we wish to sleep
we are wont to strive for a situation resembling the one in Strümpell’s
experiment. We close the most important sensory paths, the eyes, and we
endeavour to keep away from the other senses every stimulus and every
change of the stimuli acting upon them. We then fall asleep, although we
are never perfectly successful in our preparations. We can neither keep
the stimuli away from the sensory organs altogether, nor can we fully
extinguish the irritability of the sensory organs. That we may at any
time be awakened by stronger stimuli should prove to us “that the mind
has remained in constant communication with the material world even
during sleep.” The sensory stimuli which reach us during sleep may
easily become the source of dreams.
There are a great many stimuli of such nature, ranging from those that
are unavoidable, being brought on by the sleeping state or at least
occasionally induced by it, to the accidental waking stimuli which are
adapted or calculated to put an end to sleep. Thus a strong light may
force itself into the eyes, a noise may become perceptible, or some
odoriferous matter may irritate the mucous membrane of the nose. In the
spontaneous movements of sleep we may lay bare parts of the body and
thus expose them to a sensation of cold, or through change of position
we may produce sensations of pressure and touch. A fly may bite us, or a
slight accident at night may simultaneously attack more than one sense.
Observers have called attention to a whole series of dreams in which the
stimulus verified on waking, and a part of the dream content
corresponded to such a degree that the stimulus could be recognised as
the source of the dream.
I shall here cite a number of such dreams collected by Jessen[36] (p.
527), traceable to more or less accidental objective sensory stimuli.
“Every indistinctly perceived noise gives rise to corresponding dream
pictures; the rolling of thunder takes us into the thick of battle, the
crowing of a cock may be transformed into human shrieks of terror, and
the creaking of a door may conjure up dreams of burglars breaking into
the house. When one of our blankets slips off at night we may dream that
we are walking about naked or falling into the water. If we lie
diagonally across the bed with our feet extending beyond the edge, we
may dream of standing on the brink of a terrifying precipice, or of
falling from a steep height. Should our head accidentally get under the
pillow we may then imagine a big rock hanging over us and about to crush
us under its weight. Accumulation of semen produces voluptuous dreams,
and local pain the idea of suffering ill treatment, of hostile attacks,
or of accidental bodily injuries.”
“Meier (_Versuch einer Erklärung des Nachtwandelns_, Halle, 1758, p.
33), once dreamed of being assaulted by several persons who threw him
flat on the ground and drove a stake into the ground between his big and
second toes. While imagining this in his dream he suddenly awoke and
felt a blade of straw sticking between his toes. The same author,
according to Hemmings (_Von den Traumen und Nachtwandeln_, Weimar, 1784,
p. 258) dreamed on another occasion that he was being hanged when his
shirt was pinned somewhat tight around his neck. Hauffbauer dreamed in
his youth of having fallen from a high wall and found upon waking that
the bedstead had come apart, and that he had actually fallen to the
floor.... Gregory relates that he once applied a hot-water bottle to his
feet, and dreamed of taking a trip to the summit of Mount Ætna, where he
found the heat on the ground almost unbearable. After having applied a
blistering plaster to his head, a second man dreamed of being scalped by
Indians; a third, whose shirt was damp, dreamed of being dragged through
a stream. An attack of gout caused the patient to believe that he was in
the hands of the Inquisition, and suffering pains of torture (Macnish).”
The argument based upon the resemblance between stimulus and dream
content is reinforced if through a systematic induction of stimuli we
succeed in producing dreams corresponding to the stimuli. According to
Macnish such experiments have already been made by Giron de
Buzareingues. “He left his knee exposed and dreamed of travelling in a
mail coach at night. He remarked in this connection that travellers
would well know how cold the knees become in a coach at night. Another
time he left the back of his head uncovered, and dreamed of taking part
in a religious ceremony in the open air. In the country where he lived
it was customary to keep the head always covered except on such
occasions.”
Maury[48] reports new observations on dreams produced in himself. (A
number of other attempts produced no results.)
1. He was tickled with a feather on his lips and on the tip of his nose.
He dreamed of awful torture, viz. that a mask of pitch was stuck to his
face and then forcibly torn off, taking the skin with it.
2. Scissors were sharpened on pincers. He heard bells ringing, then
sounds of alarm which took him back to the June days of 1848.
3. Cologne water was put on his nose. He found himself in Cairo in the
shop of John Maria Farina. This was followed by mad adventures which he
was unable to reproduce.
4. His neck was lightly pinched. He dreamed that a blistering plaster
was put on him, and thought of a doctor who treated him in his
childhood.
5. A hot iron was brought near his face. He dreamed that _chauffeurs_[G]
broke into the house and forced the occupants to give up their money by
sticking their feet into burning coals. The Duchess of Abrantés, whose
secretary he imagined himself in the dream, then entered.
6. A drop of water was let fall on his forehead. He imagined himself in
Italy perspiring heavily and drinking white wine of Orvieto.
7. When a burning candle was repeatedly focussed on him through red
paper, he dreamed of the weather, of heat, and of a storm at sea which
he once experienced in the English Channel.
D’Hervey,[34] Weygandt,[75] and others have made other attempts to
produce dreams experimentally.
Many have observed the striking skill of the dream in interweaving into
its structure sudden impressions from the outer world in such a manner
as to present a gradually prepared and initiated catastrophe
(Hildebrandt)[35]. “In former years,” this author relates, “I
occasionally made use of an alarm clock in order to wake regularly at a
certain hour in the morning. It probably happened hundreds of times that
the sound of this instrument fitted into an apparently very long and
connected dream, as if the entire dream had been especially designed for
it, as if it found in this sound its appropriate and logically
indispensable point, its inevitable issue.”
I shall cite three of these alarm-clock dreams for another purpose.
Volkelt (p. 68) relates: “A composer once dreamed that he was teaching
school, and was just explaining something to his pupils. He had almost
finished when he turned to one of the boys with the question: ‘Did you
understand me?’ The boy cried out like one possessed ‘Ya.’ Annoyed at
this, he reprimanded him for shouting. But now the entire class was
screaming ‘Orya,’ then ‘Euryo,’ and finally ‘Feueryo.’ He was now
aroused by an actual alarm of fire in the street.”
Garnier (_Traité des Facultés de l’Âme_, 1865), reported by
Radestock,[54] relates that Napoleon I., while sleeping in a carriage,
was awakened from a dream by an explosion which brought back to him the
crossing of the Tagliamento and the bombarding of the Austrians, so that
he started up crying, “We are undermined!”
The following dream of Maury[48] has become celebrated. He was sick, and
remained in bed; his mother sat beside him. He then dreamed of the reign
of terror at the time of the Revolution. He took part in terrible scenes
of murder, and finally he himself was summoned before the Tribunal.
There he saw Robespierre, Marat, Fouquier-Tinville, and all the sorry
heroes of that cruel epoch; he had to give an account of himself, and,
after all sort of incidents which did not fix themselves in his memory,
he was sentenced to death. Accompanied by an enormous crowd, he was led
to the place of execution. He mounted the scaffold, the executioner tied
him to the board, it tipped, and the knife of the guillotine fell. He
felt his head severed from the trunk, and awakened in terrible anxiety,
only to find that the top piece of the bed had fallen down, and had
actually struck his cervical vertebra in the same manner as the knife of
a guillotine.
This dream gave rise to an interesting discussion introduced by Le
Lorrain[45] and Egger[20] in the _Revue Philosophique_. The question was
whether, and how, it was possible for the dreamer to crowd together an
amount of dream content apparently so large in the short space of time
elapsing between the perception of the waking stimulus and the
awakening.
Examples of this nature make it appear that the objective stimuli during
sleep are the most firmly established of all the dream sources; indeed,
it is the only stimulus which plays any part in the layman’s knowledge.
If we ask an educated person, who is, however, unacquainted with the
literature of dreams, how dreams originate, he is sure to answer by
referring to a case familiar to him in which a dream has been explained
after waking by a recognised objective stimulus. Scientific
investigation cannot, however, stop here, but is incited to further
research by the observation that the stimulus influencing the senses
during sleep does not appear in the dream at all in its true form, but
is replaced by some other presentation which is in some way related to
it. But the relation existing between the stimulus and the result of the
dream is, according to Maury,[47] “une affinité quelconque mais qui
n’est pas unique et exclusive” (p. 72). If we read, _e.g._, three of
Hildebrandt’s “Alarm Clock Dreams,” we will then have to inquire why the
same stimulus evoked so many different results, and why just these
results and no others.
(P. 37). “I am taking a walk on a beautiful spring morning. I saunter
through the green fields to a neighbouring village, where I see the
natives going to church in great numbers, wearing their holiday attire
and carrying their hymn-books under their arms. I remember that it is
Sunday, and that the morning service will soon begin. I decide to attend
it, but as I am somewhat overheated I also decide to cool off in the
cemetery surrounding the church. While reading the various epitaphs, I
hear the sexton ascend the tower and see the small village bell in the
cupola which is about to give signal for the beginning of the devotions.
For another short while it hangs motionless, then it begins to swing,
and suddenly its notes resound so clearly and penetratingly that my
sleep comes to an end. But the sound of bells comes from the alarm
clock.”
“A second combination. It is a clear day, the streets are covered with
deep snow. I have promised to take part in a sleigh-ride, but have had
to wait for some time before it was announced that the sleigh is in
front of my house. The preparations for getting into the sleigh are now
made. I put on my furs and adjust my muff, and at last I am in my place.
But the departure is still delayed, until the reins give the impatient
horses the perceptible sign. They start, and the sleigh bells, now
forcibly shaken, begin their familiar janizary music with a force that
instantly tears the gossamer of my dream. Again it is only the shrill
sound of my alarm clock.”
Still a third example. “I see the kitchen-maid walk along the corridor
to the dining-room with several dozen plates piled up. The porcelain
column in her arms seems to me to be in danger of losing its
equilibrium. ‘Take care,’ I exclaim, ‘you will drop the whole pile.’ The
usual retort is naturally not wanting—that she is used to such things.
Meanwhile I continue to follow her with my worried glance, and behold!
at the door-step the fragile dishes fall, tumble, and roll across the
floor in hundreds of pieces. But I soon notice that the noise continuing
endlessly is not really a rattling but a true ringing, and with this
ringing the dreamer now becomes aware that the alarm clock has done its
duty.”
The question why the dreaming mind misjudges the nature of the objective
sensory stimulus has been answered by Strümpell,[66] and almost
identically by Wundt,[76] to the effect that the reaction of the mind to
the attacking stimuli in sleep is determined by the formation of
illusions. A sensory impression is recognised by us and correctly
interpreted, i.e. it is classed with the memory group to which it
belongs according to all previous experience, if the impression is
strong, clear, and long enough, and if we have the necessary time at our
disposal for this reflection. If these conditions are not fulfilled, we
mistake the objects which give rise to the impression, and on its basis
we form an illusion. “If one takes a walk in an open field and perceives
indistinctly a distant object, it may happen that he will at first take
it for a horse.” On closer inspection the image of a cow resting may
obtrude itself, and the presentation may finally resolve itself with
certainty into a group of people sitting. The impressions which the mind
receives during sleep through outer stimuli are of a similar indistinct
nature; they give rise to illusions because the impression evokes a
greater or lesser number of memory pictures through which the impression
receives its psychic value. In which of the many spheres of memory to be
taken into consideration the corresponding pictures are aroused, and
which of the possible association connections thereby come into force,
this, even according to Strümpell, remains indeterminable, and is left,
as it were, to the caprice of the psychic life.
We may here take our choice. We may admit that the laws of the dream
formation cannot really be traced any further, and therefore refrain
from asking whether or not the interpretation of the illusion evoked by
the sensory impression depends upon still other conditions; or we may
suppose that the objective sensory stimulus encroaching upon sleep plays
only a modest part as a dream source, and that other factors determine
the choice of the memory picture to be evoked. Indeed, on carefully
examining Maury’s experimentally produced dreams, which I have purposely
reported in detail, one is apt to think that the experiment really
explains the origin of only one of the dream elements, and that the rest
of the dream content appears in fact too independent, too much
determined in detail, to be explained by the one demand, viz. that it
must agree with the element experimentally introduced. Indeed one even
begins to doubt the illusion theory, and the power of the objective
impression to form the dream, when one learns that this impression at
times experiences the most peculiar and far-fetched interpretations
during the sleeping state. Thus B. M. Simon[63] tells of a dream in
which he saw persons of gigantic stature[H] seated at a table, and heard
distinctly the awful rattling produced by the impact of their jaws while
chewing. On waking he heard the clacking of the hoofs of a horse
galloping past his window. If the noise of the horse’s hoofs had
recalled ideas from the memory sphere of “Gulliver’s Travels,” the
sojourn with the giants of Brobdingnag and the virtuous
horse-creatures—as I should perhaps interpret it without any assistance
on the author’s part—should not the choice of a memory sphere so
uncommon for the stimulus have some further illumination from other
motives?
II. _Internal (Subjective) Sensory Stimuli._—Notwithstanding all
objections to the contrary, we must admit that the rôle of the objective
sensory stimuli as a producer of dreams has been indisputably
established, and if these stimuli seem perhaps insufficient in their
nature and frequency to explain all dream pictures, we are then directed
to look for other dream sources acting in an analogous manner. I do not
know where the idea originated that along with the outer sensory stimuli
the inner (subjective) stimuli should also be considered, but as a
matter of fact this is done more or less fully in all the more recent
descriptions of the etiology of dreams. “An important part is played in
dream illusions,” says Wundt[36] (p. 363), “by those subjective
sensations of seeing and hearing which are familiar to us in the waking
state as a luminous chaos in the dark field of vision, ringing, buzzing,
&c., of the ears, and especially irritation of the retina. This explains
the remarkable tendency of the dream to delude the eyes with numbers of
similar or identical objects. Thus we see spread before our eyes
numberless birds, butterflies, fishes, coloured beads, flowers, &c. Here
the luminous dust in the dark field of vision has taken on phantastic
figures, and the many luminous points of which it consists are embodied
by the dream in as many single pictures, which are looked upon as moving
objects owing to the mobility of the luminous chaos. This is also the
root of the great fondness of the dream for the most complex animal
figures, the multiplicity of forms readily following the form of the
subjective light pictures.”
The subjective sensory stimuli as a source of the dream have the obvious
advantage that unlike the objective stimuli they are independent of
external accidents. They are, so to speak, at the disposal of the
explanation as often as it needs them. They are, however, in so far
inferior to the objective sensory stimuli that the rôle of dream
inciter, which observation and experiment have proven for the latter,
can be verified in their case only with difficulty or not at all. The
main proof for the dream-inciting power of subjective sensory
excitements is offered by the so-called hypnogogic hallucinations, which
have been described by John Müller as “phantastic visual
manifestations.” They are those very vivid and changeable pictures which
occur regularly in many people during the period of falling asleep, and
which may remain for awhile even after the eyes have been opened.
Maury,[48] who was considerably troubled by them, subjected them to a
thorough study, and maintained that they are related to or rather
identical with dream pictures—this has already been asserted by John
Müller. Maury states that a certain psychic passivity is necessary for
their origin; it requires a relaxation of the tension of attention (p.
59). But in any ordinary disposition a hypnogogic hallucination may be
produced by merging for a second into such lethargy, after which one
perhaps awakens until this oft-repeated process terminates in sleep.
According to Maury, if one awakens shortly thereafter, it is often
possible to demonstrate the same pictures in the dream which one has
perceived as hypnogogic hallucinations before falling asleep (p. 134).
Thus it once happened to Maury with a group of pictures of grotesque
figures, with distorted features and strange headdresses, which obtruded
themselves upon him with incredible importunity during the period of
falling asleep, and which he recalled having dreamed upon awakening. On
another occasion, while suffering from hunger, because he kept himself
on a rather strict diet, he saw hypnogogically a plate and a hand armed
with a fork taking some food from the plate. In his dream he found
himself at a table abundantly supplied with food, and heard the rattle
made by the diners with their forks. On still another occasion, after
falling asleep with irritated and painful eyes, he had the hypnogogic
hallucination of seeing microscopically small characters which he was
forced to decipher one by one with great exertion; having been awakened
from his sleep an hour later, he recalled a dream in which there was an
open book with very small letters, which he was obliged to read through
with laborious effort.
Just as in the case of these pictures, auditory hallucinations of words,
names, &c., may also appear hypnogogically, and then repeat themselves
in the dream, like an overture announcing the principal motive of the
opera which is to follow.
A more recent observer of hypnogogic hallucinations, G. Trumbull
Ladd,[40] takes the same path pursued by John Müller and Maury. By dint
of practice he succeeded in acquiring the faculty of suddenly arousing
himself, without opening his eyes, two to five minutes after having
gradually fallen asleep, which gave him opportunity to compare the
sensations of the retina just vanishing with the dream pictures
remaining in his memory. He assures us that an intimate relation between
the two can always be recognised, in the sense that the luminous dots
and lines of the spontaneous light of the retina produced, so to speak,
the sketched outline or scheme for the psychically perceived dream
figures. A dream, _e.g._, in which he saw in front of him clearly
printed lines which he read and studied, corresponded to an arrangement
of the luminous dots and lines in the retina in parallel lines, or, to
express it in his own words: “The clearly printed page, which he was
reading in the dream, resolved itself into an object which appeared to
his waking perception like part of an actual printed sheet looked at
through a little hole in a piece of paper, from too great a distance to
be made out distinctly.” Without in any way under-estimating the central
part of the phenomenon, Ladd believes that hardly any visual dream
occurs in our minds that is not based on material furnished by this
inner condition of stimulation in the retina. This is particularly true
of dreams occurring shortly after falling asleep in a dark room, while
dreams occurring in the morning near the period of awakening receive
their stimulation from the objective light penetrating the eye from the
lightened room. The shifting and endlessly variable character of the
spontaneous luminous excitation of the retina corresponds exactly to the
fitful succession of pictures presented to us in our dreams. If we
attach any importance to Ladd’s observations, we cannot underrate the
productiveness of this subjective source of excitation for the dream;
for visual pictures apparently form the principal constituent of our
dreams. The share furnished from the spheres of the other senses, beside
the sense of hearing, is more insignificant and inconstant.