The last decade of the nineteenth century was marked by acute and widespread anxiety over a range of ‘undesirables,’ including ‘the biologically unfit, the criminal classes, the “lower races”, the alcoholic, the syphilitic, the degenerate artist, the idiot, the moron, the masculinizing female, the feminizing male.’ In The Crowd: A Study of the Popular Mind (1896), Gustave Le Bon identified urbanization and its consequences as probable causes of the ‘epidemic’ of insanity. Crowds, he observed, were extremely mobile and volatile, excited randomly by whatever was happening at that moment, incapable of premeditation, and difficult to govern. For Le Bon, what qualified an act as ‘insane’ was not its illogical, strange or surreal nature, but rather its lack of agency: ‘insanity’ meant, first of all, the absence of will or consciousness. Similarly, in Degeneration (1892), Max Nordau, a prolific writer of Austro-Hungarian Jewish origins who studied and practiced medicine in Paris under Jean-Martin Charcot, located insanity or degeneracy in the realm of ideation, specifically in the separation of the realm of ideation from the realm of action:

Degeneration was dedicated to Cesare Lombroso, whose Criminal Man, in which Lombroso developed his famous theory of the born criminal marked by physical and psychological abnormalities, was first published in 1876. Lombroso called his new field of research ‘criminal anthropology.’ Having worked as a military doctor during the wars of Italian unification, he used soldiers to develop his approach of measuring and observing the bodies of his patients. He compared the morally insane with the criminal in terms of the skull, physiognomy, analgesia, tattooing, sexuality, moral sense, and affection. Lumping together all social undesirables into one undifferentiated group, he compared them to the insane and to control groups of ‘healthy’ men, usually soldiers.