One of the author’s patients, a sexually hyperaesthetic woman of thirty years of age, who always had a supply of lovers besides her husband, found great delight in jacendo nuda in genibus amati et ab eo verberata in nudis natibus. When first told about this peculiar desire, the author attributed this desire to her natural hyperexcitation. In this state every impression, produced by the consort, independently of the manner of its production, is per se attended with lustful pleasure. But later on, when he learned that she found more satisfaction in concubitu if preceded by such a spanking, and that the husband often had to gratify her in this manner even in the middle of the night, there was no doubt that hers was a case of a psychical anomaly in which the sexual instinct was partly made insensible to the normal charms of the consort. Her perverse desire was, therefore, of a masochistic nature. Of the same masochistic nature was the frigidity of the Duchess Leonore Gonzaza of Mantua. Aloisia Sigea says that her frigidity could only be removed by a flagelation by her mother ante coitum: “Virgis Leonora, parentis suae manu ad hanc diem nullam ex Venere ceperat voluptatem. Hoc vero temporis momento vehementissime mota est, lacessiti iterum verberibus lumbi, clunes et femora ad venerem incensi.” Generally, female masochistic patients are unconscious of the abnormality of their desires and never come to the physician’s office. Their pathological condition is only accidentally discovered, when complicated with other anomalies. It may be also noted that the courts of justice never or very rarely have any dealings with cases of masochism, whether in men or in women, as may happen in sadism. The patient will never go so far in his or her perverse desire for suffering that the injury inflicted may become criminal. For the extreme consequences of masochism, such as murder and serious injury, as sometimes found in sadism, are avoided through the instinct of self-preservation. _Sadism._—While masochism is a pathological growth of specifically feminine mental elements, where the patient finds delight in suffering pain, in sadism the patient seeks lustful excitement in inflicting pain. Sadism hence represents a pathological intensification of the masculine mental character. Sadism is so-called after the Marquis de Sade, who during the French Revolution devoted himself to the writing of obscene books which had lust and cruelty for their theme.