A young officer, home on short leave of absence, asked me to treat his mother-in-law, who was living in the happiest surroundings and yet was embittering her own and her family’s lives by a nonsensical idea. I found her a well-preserved lady, fifty-three years of age, of a friendly, simple disposition, who gave without hesitation the following account of herself. She is most happily married, and lives in the country with her husband who manages a large factory. She cannot say enough of her husband’s kindness and consideration; theirs had been a love-marriage thirty years ago, since when they had never had a cloud, a quarrel, or a moment’s jealousy. Her two children have both married well, but her husband’s sense of duty keeps him still at work. A year before, an incredible and, to her, incomprehensible thing happened. She received an anonymous letter telling her that her excellent husband was carrying on an intrigue with a young girl, and believed it on the spot—since then her happiness has been destroyed. The details were more or less as follows: she had a housemaid with whom she discussed confidential matters, perhaps rather too freely. This young woman cherished a positively venomous hatred for another girl who had succeeded better in life than herself, although of no better origin. Instead of going into service, the other young woman had had a commercial training, been taken into the factory and, owing to vacancies caused by the absence of staff on service in the field, had been promoted to a good position. She lived in the factory, knew all the gentlemen, and was even addressed as “Miss.” The other one who had been left behind in life was only too ready to accuse her former schoolmate of all possible evil. One day our patient and her housemaid were discussing an elderly gentleman who had visited the house and of whom it was said that he did not live with his wife but kept a mistress. Why, she did not know, but she suddenly said: “I cannot imagine anything more awful than to hear that my husband had a mistress.” The next day she received by post an anonymous letter in disguised handwriting which informed her of the very thing she had just imagined. She concluded—probably correctly—that the letter was the handiwork of her malicious housemaid, for the woman who was named as the mistress of her husband was the very girl who was the object of this housemaid’s hatred. Although she at once saw through the plot and had seen enough of such cowardly accusations in her own surroundings to place little credence in them, our patient was nevertheless prostrated by this letter. She became terribly excited and at once sent for her husband to overwhelm him with reproaches. The husband laughingly denied the accusation and did the best thing he could. He sent for the family physician (who also attended the factory), and he did his best to calm the unhappy lady. The next thing they did was also most reasonable. The housemaid was dismissed,