The symptoms of the disease had been described in antiquity, by Hippocrates, but there was still no effective treatment for it. It was a hopeless, loathsome, incomprehensible thing and its victims were subjected to a drastic regime. In Flaubert's case, a device like a small tap, known as a seton collar, was attached to his neck to facilitate regular bleeding. Purgative mercury massages were applied. Alcohol, tobacco, caffeine and meat were forbidden. The patient was secluded and carefully watched over.

The treatment wore a rational modern disguise. Yet from beneath that disguise it spoke in the older language of religious symbolism. However unscientific to our eyes, it makes good sense if we consider it as a ritual of purification. Victim and family moved out to Croisset, a holy place beside a great river, thus escaping all the malignant impurities that hung in the air of the city. At Croisset the victim was symbolically cleansed of his pollution, through repeated washing, bloodletting and swimming.

Flaubert subsequently observed and described his nameless condition with great acuity. We might say, from the evidence of his letters, that he learnt to live with it, to inhabit it imaginatively as a unique province of his mind. Perhaps a name would have kept him out, discouraged him from undertaking that terrifying quest. Once he knew that he could survive the recurrent intimate disaster of the attack, he could begin to learn from it, even to experiment with it. His epilepsy, or rather what he did with what they called epilepsy, confirmed in him a curious early affinity for the most extreme varieties of religious experience, the ecstatic visions and the diabolical torments of the saints.

It was George Sand, Flaubert's generously sympathetic confidante, who urged Flaubert to make something of his sufferings. ‘Describe your martyrdom,’ she wrote in January 1875. ‘There is a fine book to be written there.’13 Reluctantly won over to the idea, Flaubert did not begin with a flamboyantly dramatic martyrdom – the obvious, fiery-torment, agony-in-the-desert variety. He had done that already, in The Temptation of Saint Antony. There was another kind of martyrdom, the slow stifling of the spirit, the quiet sinking into decrepitude. This was the modern martyrdom. He had, after all, recently witnessed the mental and physical dissolution of his mother during the final years of her life. He could feel in his own mind the first keen vexations of old age: his friends dying, his money disappearing, his house falling apart, his faculties decaying. Here was a subject close to home.

He had a clear sense of what he wanted his martyr-tale to be. Its ‘underlying humanity’14 would confound all those who had ever chided him for treating his characters sadistically. This time there would be no amputations, no arsenic poisoning, no flaying of captives, no dead babies (not in the first story, at least; there would be plenty of that sort of thing in the other two tales). This would be the intimate history of the love that never found an object. He would draw upon the scenes of his own early years: the seaside holiday landscapes, the memories of his younger sister who had died. He would borrow the forlorn, frozen egocentricities of his mother's lengthy widowhood. He would take the woman's part, as he had done once before, with Emma Bovary.

Feminization was much better than castration. It was reversible and it connected him to all that was most radically original in his own artistic personality. He would become a servant, pious, illiterate and loving.