A real case came under my observation a few months ago, and which is equally apposite to the subject. A young man had become insane from habitual intoxication, and during the violence of his complaint had attempted to destroy himself. Under a supposed imputation of having unnatural dispositions he had amputated his penis, with a view of precluding any future insinuations of that nature. For many months after he was admitted into the hospital, he continued in a state which obliged him to be strictly confined, as he constantly meditated his own destruction. On a sudden he became apparently well, was highly sensible of the delusion under which he had laboured, and conversed as any other person upon the ordinary topics of discourse. There was, however, something in the reserve of his manner, and peculiarity of his look, which persuaded me that he was not well, although no incoherence of ideas could be detected in his conversation. I had observed him for some days to walk rather lame, and once or twice had noticed him sitting with his shoes off, rubbing his feet. On enquiring into the motives of his doing so, he replied, that his feet were blistered, and wished that some remedy might be applied to remove the vesications. When I requested to look at his feet, he declined it and prevaricated, saying, that they were only tender and uncomfortable. In a few days afterwards, he assured me they were perfectly well. The next evening I observed him, unperceived, still rubbing his feet, and then peremptorily insisted on examining them. They were quite free from any disorder. He now told me with some embarrassment, that he wished much for a confidential friend, to whom he might impart a secret of importance. Upon assuring him that he might trust me, he said, that the boards on which he walked, (the second story) were heated by subterraneous fires, under the direction of invisible and malicious agents, whose intentions, he was well convinced, were to consume him by degrees.
From these considerations I am inclined to think, that a _lucid interval_ includes all the circumstances which I have enumerated in my definition of it. If the person who is to examine the state of the patient's mind be unacquainted with his peculiar opinions, he may be easily deceived, because, wanting this information, he will have no clue to direct his enquiries, and madmen do not always, nor immediately intrude their incoherent notions into notice. They have sometimes such a high degree of controul over their minds, that when they have any particular purpose to carry, they will affect to renounce those opinions which shall have been judged inconsistent: and it is well known that they have often dissembled their resentment, until a favourable opportunity has occurred of gratifying their revenge.