The question is continually asked, why are certain dreams so vivid and so easily remembered, while others are of the faintest and most evanescent character? My own experience leads me to believe that there is a morbid element underlying all unusually vivid dreams. It is not merely because of differences in the depth of sleep. The flitting fancies which occupy the introduction and the termination of sleep, rarely possess any power to fix the attention or to linger in memory. But, if the body be disturbed by anything which causes a departure from the even course of health, such as follows unusual or violent emotion, or an attack of illness, or an insufficient alimentation, or great and sudden changes of atmospheric pressure, the visions of the night become wonderfully exaggerated in every particular. During a voyage at sea, while suffering considerably with thirst, one night I dreamed that a fountain of sparkling water suddenly appeared before me. A young girl dipped a pitcher in the flowing stream, and held it out, all dripping with delicious coolness, for me to drink. Pressing eagerly forward, I awoke, to find myself sitting up in my narrow berth, with hands extended for the draught. Every narrative of shipwreck is filled with similar experiences. Slow starvation is always accompanied by dreams of singular intensity and persistence. As an illustration of the corresponding influence of previous emotion, I may cite the experience of a friend who had been greatly shocked by reading the account of the manner in which the lunatic, Freeman, had killed his little son in imitation of Abraham’s contemplated sacrifice of Isaac. This gentleman dreamed that he was about to sacrifice his favorite daughter. He called her to him; told her that he was about to cut off her head as a religious sacrifice; and took up the knife for that purpose. She exclaimed, “Oh, papa! I have never disobeyed you yet!” and extended her neck, to receive the fatal stroke, when he awoke, trembling in every limb, and drenched with perspiration. For a long time the horror of this dream affected him as terribly as if it had been an actual experience.