In the month of February, 1814, I was living in the same house with a young gentleman, the son of a peer of the United Kingdom, who was at that time under my care in a very alarming state of health; and who had been, for several days, in a state of violent delirium. The close attention which his case required from me, together with a degree of personal attachment to him, had rendered me extremely anxious about him; and as my usual hours of sleep suffered a great degree of interruption from the attendance given to him, I was from that cause alone rendered more than usually liable to the attacks of Night-Mare, which consequently intruded itself every night upon my slumbers. The young gentleman in question, from the violence of his delirium, was with great difficulty kept in bed; and had once or twice eluded the vigilance of his attendants, and jumped out of bed: an accident, of which I was every moment dreading a repetition. I awoke from my sleep one morning about four o’clock, at least it appeared to me that I awoke, and heard distinctly the voice of this young gentleman, who seemed to be coming hastily up the stairs leading to my apartment, calling me by name, in the manner he was accustomed to do in his delirium; and immediately after I saw him standing by my bed-side holding the curtains open, expressing all that wildness in his looks, which accompanies violent delirium. At the same moment, I heard the voices of his two attendants coming up the stairs in search of him, who likewise came into the room, and took him away. During all this scene I was attempting to speak, but could not articulate; I thought, however, that I succeeded in attempting to get out of bed, and assisting his attendants in removing him out of the room, after which I returned to bed, and instantly fell asleep. When I waited upon my patient in the morning, I was not a little surprised to find that he was asleep; and was utterly confounded on being told that he had been so all night; and as this was the first sleep he had enjoyed for three or four days, the attendants were very minute in detailing the whole particulars of it. Although this account appeared inconsistent with what I conceived I had seen, and with what I concluded they knew as well as myself, I did not for some time perceive the error into which I had been led, till I observed, that some of my questions and remarks were not intelligible; then I began to suspect the true source of the error, which I should never have discovered, had not experience rendered these hallucinations familiar to me. But the whole of this transaction had so much consistency and probability in it, that I might, under different circumstances, have remained for ever ignorant of having been imposed upon, in this instance, by my senses. The idea which I myself entertained on the subject was this; that when the person came to my bed-side, I was actually labouring under a paroxysm of Night-Mare,