Marcel Proust comes to literary maturity at a watershed moment in the evolution of late nineteenth- to early twentieth-century thinking about illness. On the one hand, he is the uneasy inheritor of nineteenth-century obsessions about hysteria and maladies of the nervous system. Many of his characters suffer from problems of the nerves, his asthmatic Narrator in the first instance, not to speak of Proust's friends such as the writers Daniel Halévy and Anna de Noailles. At another level, the fin de siècle is preoccupied with the idea of degeneration, both of the tainted individual and of society itself, and traces of this sense of downwardness persist in the final volumes of À la recherche du temps perdu. A more specific, personal problem posed itself for Proust as the century turned: in 1898, a prominent French psychiatrist was still writing that most doctors considered ‘sexual inversion, the spontaneous sensual, sentimental or intellectual attraction to a person of the same sex, as a sign of degeneracy’.

Increasingly, as Freud and Breuer published their first essays on hysteria, medicine was turning away from the physical and beginning to discover psychosomatic maladies. Proust reached his twenties in the heyday of a new psycho-medical condition called neurasthenia – a kind of latter-day chronic fatigue syndrome – the symptoms of which (episodic nervous exhaustion and a lack of willpower and decisiveness) began to be widely identified, particularly in men. During the same period, there was much discussion of willpower deficits, especially after the psychologist Théodule Ribot published Les Maladies de la volonté [Ailments of the Will] in 1883. In the wake of that essay, a rising star, the novelist and critic Paul Bourget, became a kind of prophet of the weak-will syndrome in literary personalities. According to Bourget, willpower deficit was not only a seminal idea in the novels of the Goncourt brothers, it was the underlying theme of Zola's Rougon-Macquart and at the heart of Alphonse Daudet's characters. The same malady, he wrote in a text that Proust would have read avidly, almost prevented Maxime Du Camp from electing the proper form for his writing. Du Camp dabbled in every possible writing genre before realizing that the correct vehicle for his thought was history, the history of Paris.