linguistic:paraphrasing, information:extraction, structural:expansion
18th century

Immanuel Kant regarded masturbation as a violation of the moral law. In The Metaphysics of Morals (1797), he made the a posteriori argument that "such an unnatural use of one's sexual attribute" strikes "everyone upon his thinking of it" as "a violation of one's duty to himself", and suggested that it was regarded as immoral even to give it its proper name (unlike the case of the similarly undutiful act of suicide). He went on, however, to acknowledge that "it is not so easy to produce a rational demonstration of the inadmissibility of that unnatural use", but ultimately concluded that its immorality lay in the fact that "a man gives up his personality … when he uses himself merely as a means for the gratification of an animal drive". His arguments were rejected as flawed by ethicists of the 20th and 21st centuries.