ABSTRACT
The nineteenth century saw the gradual replacement of predominantly Christian taxonomies of sexual sin with biological and psychological models, based on congenital, psychiatric and legal conceptions of the modern subject. Pre-modern sexual deviance was essentially seen as a crime 'against nature'. Aquinas defines any sexual act from which procreation cannot follow as 'unnatural vice'. The modern perversions, which above all include homosexuality, sadism, masochism, fetishism, voyeurism and exhibitionism, are symptomatic of particular cultural anxieties and concerns. Most sexologists seek primarily to explain the aetiologies of the perversions so that they can be understood, contained and possibly even cured. In the course of the late nineteenth century, the cultural emphasis shifted from the problem of masturbation, which preoccupied the medical establishment in the eighteenth and at the beginning of the nineteenth century, to homosexuality. Ellis's theory, like those in most other sexological works, is framed around a number of case studies.
