“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.