The possibility of thus suggesting, and in some degree guiding, the form and course of a dream, has been often demonstrated.[58] One of my early schoolmates, a boy of remarkably susceptible nervous temperament, furnished an excellent example of this species of direction. Tickling his nose with a straw made him dream that a dragon-fly was assaulting his face. On another occasion, a few drops of vinegar placed upon his tongue caused him to dream of eating oranges. Again, one of his companions roguishly breathing in his ear the statement that the schoolmaster was after him with a long rattan, he bounded out of bed, and could scarcely be restrained from bursting out of doors in his evident alarm. I was myself awakened, one night, by the ringing, as it seemed, of my doorbell; but, hastening at once to the door, no one was there. As I was expecting a call from a certain patient, I concluded that the bell had been rung by an impatient messenger who could not wait. Falling again asleep, I was a second time startled by a similar ring. Looking out of the window above the door, it was evident that no one was there. I finally concluded that the sound must have been perceived in a dream, and I recalled the fact that each time, as I woke, the sound of a carriage, passing the house, had attracted my attention. Undoubtedly, the state of expectancy in which I was sleeping had operated as the predisposing cause of dreaming, and the noise of wheels upon the pavement had served as the exciting cause of a dream in which the sound-vibrations communicated to the brain had produced by an association of ideas the particular perception which, though asleep, I was waiting to receive. In certain cases the impression produced by a dream is so vivid that a considerable time after waking must elapse before it can be relegated to its true position in the world of hallucinations. Dreaming, once, that my wife called to me from another room, I instantly awoke; and only the fact that she was with me could satisfy me that it was all a dream. Taine[59] relates that “M. Baillarger dreamed one night that a certain person had been appointed editor of a newspaper; in the morning he believed it to be true, and mentioned it to several persons who were interested to hear it;--the effect of the dream persisted all the forenoon, as strongly as that of a real sensation; at last, about three o’clock, as he was stepping into his carriage, the illusion passed off; he comprehended that he had been dreaming.” The following incident from the experience of Prof. Jessen, physician to the insane asylum in Homheim, near Kiel,[60] still further illustrates this form of hallucination: