Persons who suffer from actual trouble or ill treatment easily develop a morbid sense of injury, just as under similar conditions they may become insane. Unable to estimate the precise amount of their real grievance, there is an easy mental overflow into the fictitious ones. It is for this reason that the narrative of a real trouble or quarrel is so fraught with calumnious arraignment of others that it is unreliable until we have heard the "other side of the story," and that when disputants meet and explanations follow they often find that they have no _casus belli_. In the examination of the alleged insane for commitment we have constantly to separate the real from the imaginary troubles. Mr. F---- was the subject of such examination. He was suffering from heart disease, and thereby compelled to remain at home idle. His wife was supporting the family by keeping boarders, and he began to develop a morbid jealousy of her. He annoyed her by a constant surveillance and suspicion of her every act, which amounted at times to the delusion that she was unfaithful to him, and which culminated one night in an outbreak in which the police figured. It was difficult to separate his real from his imaginary grievances, for his wife had ceased to have any affection for him, though his delusion in regard to her unfaithfulness was unfounded and had been grafted upon his real trouble. Sent to a general hospital, he improved, and was reported "not insane." Circumstances requiring a hard struggle for existence, disappointment without apparent cause, coupled with a certain sentimental cast of mind, often prevent the correct estimation of the wrongs suffered and the proper relation of undoubted misfortunes. In the insane the sense of injury or its analogue--delusions of persecution--appears in numerous shapes. Thus patients are defrauded, or conspired against, or acted upon by witchcraft, magnetism, electricity, or poisoned, or preached against, or subjected to disagreeable odors. Sometimes the delusions are but ill-defined and vague. Often it is possible to trace them to their underlying disordered sense impression or the particular environment or to vestiges of outgrown beliefs. They appear in depressed states of melancholia as well as in the exalted states of mania and paranoia. In melancholia they accompany a feeling of worthlessness which is the patient's explanation of his persecution--i. e., he is unworthy of better treatment. In paranoia the patient believes the persecution to be prompted by fear or envy of him, and there is consequently a feeling of self-importance--a morbid egotism which is in direct proportion to the magnitude or complexity of the ideas of persecution. Indeed, it is probable that these ideas of persecution, acting on a potentially melancholic or a potentially paranoiac mind, whatever these may be, determine the type that these mental diseases take.