Whosoever has carefully studied nervous diseases, can have no doubt as to the analogy of nightmare and madness; the curious facts that we have witnessed, leave no uncertainty on the subject. A distinguished writer believed that he flew in the air. We have seen him, under the influence of this hallucination, uttering inarticulate sounds - his hair bristling, his countenance full of terror. At such times he would exclaim: "How surprising! I fly like the wind! I pass over mountains and precipices!" For several seconds after awaking, he still imagined himself floating in the air.

One species of nightmare we have often noticed. The subject of it feels that he is skimming over the ground with extreme rapidity, pursued or threatened by dangers from which he is conscious of an utter inability to escape. He awakes with a vague sense of uneasiness, and experiences the fatigue resulting from a long walk.

In nervous persons, nightmare is occasioned by painful emotions. A young and delicate lady, very excitable, was accustomed to avoid listening to the recital of tales of terror, knowing from experience that disturbed slumber would result from the indulgence. A departure from her usual precaution would be followed by nightmare, with its attendant horrors. Towards midnight she would become restless; sighs and broken sentences, accompanied with extreme agitation, would follow, and her body become bathed in perspiration. On being awakened by her husband, she would utter fearful cries, fancying she was surrounded by robbers and assassins ready to destroy her.

In infancy and adolescence, the nightmare makes its approaches in the following manner: The individual attacked by it imagines himself on the edge of the bed or of a precipice, and about to fall. He feels that nothing can save him from the danger; and he looks with an eye of terror on the gulf below; an irresistible force drives him on, and he awakes with the shock. Sometimes the images that affect children are of so gay a nature as to produce immoderate laughter.

At other times, the patient imagines that robbers are breaking into his house; he hears them coming up the stairs; he tries to fly; an irresistible power fixes him to the spot. He is exhausted with fruitless efforts; he feels as though he were transformed into a block of stone, incapable of motion; or, if he is standing, as though his feet had taken root in the soil. The individual who is a prey to this hallucination, exhibits extreme agitation; he wishes to cry out, to call for help, but his voice fails him; he cannot utter a sound. The imminence of the danger, even the mortal blow, hastens the crisis; he awakes, filled with terror, bathed in perspiration, with a quickened pulse, and a sensation of oppression and uneasiness, which ceases, however, in a few seconds.

Among the numerous varieties of nightmare, we must not pass over that which consists in believing one's self condemned to death. We see all the preparations for execution; we mount the scaffold; the head falls; and yet we are still conscious, as if nothing had happened. A peculiarity that we have nowhere seen mentioned is, that a person who has suffered from an attack of nightmare may be tormented with it several days in succession, at the same hour and under a similar form. A lady felt uneasy in her sleep; soon, there appeared an enemy, who pursued her in order to kill her. She awoke with a start; on the next day the same vision returned, and continued to return for several days in succession. As the hour of rest approached, she was oppressed by an indefinable terror; her sleep was troubled, and she yielded to it, despite of herself. By degrees, this painful sensation diminished and she became calm.

A young man told us that, for several successive nights, persons placed themselves at the foot of his bed and attempted to draw off the sheets; a struggle occurred; they succeeded, and as soon as he was entirely uncovered, the fit subsided.

In other cases, the hallucinations of nightmare, however painful, exhibit no external signs of their presence. A physician who is accustomed to reading in his bed, has been told by his wife, on her awaking, that she had had a long and frightful nightmare; he had not perceived in her the slightest agitation.

It may sometimes happen that persons subject to this indisposition are conscious of the non-reality of what is passing; and reason with themselves as though they were awake, in order to prove that these sensations are false. A young lady saw the wall opposite open, and a death's head come out and fix itself on to a skeleton, which advanced towards her. Convinced that this apparition was an illusion, she talked aloud to herself to gain courage; but the uneasiness always ended in awaking her. Some authors have described a variety of nightmare, in which it appears that a cat, or some other animal, or a monster, places itself on the stomach. Great oppression is felt in that region; every effort is made to get rid of this imaginary being, whose weight stifles, whilst it freezes the blood with horror.*

In the different cases here mentioned, the hallucinations in nightmare have ceased on waking, but it may happen that they will continue in a waking state, when they are taken for realities. The nightmare is then combined with mental alienation.