For Bénédict-Augustin Morel, the devout Catholic psychiatrist who, in 1857, established the nosological category of ‘degeneration’, the human being was not the product of a gradual evolution of the species. On the contrary, modern man was, rather, the ‘morbid deviation from an original type’, a degenerate descendant of the Adamic Urmensch of Creation, and the primary cause of this dégénérescence– his name for the progressive process of pathological change manifested in visible and gross physical deformity– was original sin itself. Morel was thus responsible for the lasting impression of immorality being both causal and symptomatic in this process of degeneration: physical decadence led to intellectual and moral decay, and vice versa. dégénérescence, in other words, is at root a medicalised lapsarian myth, a potent mixture of Christian theology and Lamarckian theories of inheritance. For degeneracy was transmitted by hereditary means and intensified in successive generations, becoming, ultimately, self-perpetuating. In other words, children inherit the ‘sins of the fathers’, the biological and moral flaws of their parents, and transmit these defects to their own offspring in heightened form until the fourth generation, condemned to congenital idiocy and sterility, marks the end of the degenerate line.

Given the fact that the concept of dégénérescence was freighted with such moral-religious implications, it is significant that it should inflect and infect so much of Nietzsche's writing.