All those interested in Gustave Flaubert's illness, during his lifetime as well as after his death, have agreed that he had epilepsy. The one important exception is Jean-Paul Sartre, who, in the 2800 pages of his "Idiot de la famille" claimed that Flaubert was a hysteric with very moderate intelligence who somatized his neurosis in the form of seizures. These, in Sartre's views, were moreover probably hysterical, but possibly epileptic resulting from the existence of a psychogenic epilepsy bred from the neurosis. The basis for this neurosis could have originated at the time of Gustave's birth, as this occurred between those of two brothers who both died young, and as his mother had wished for a daughter. Further development of the neurosis might have taken place during a temporary phase of learning difficulties, exaggerated and exploited by his father to make his youngest son the idiot of a family in which the eldest son was the dauphin. Destroyed in this way, Gustave would have sought refuge in passivity and could have developed a hatred for his father and for his elder brother, who he would have liked to kill before killing himself. But, unable to carry out his wishes and desiring both to die and to survive, Gustave, adolescent, might have chosen the pathway of "false deaths", as exemplified by the seizures. Modern epileptology data enables not only to confirm the epileptic etiology and to discount the hysterical nature of the fits, but also: 1. to establish precise details of the site and nature of the cerebral lesions responsible for the attacks: neonatal atrophy or vascular malformation of the occipitotemporal cortex of the left hemisphere, the only lesion capable of provoking: a) the phosphenes marking the onset of the seizures; b) the intellectual manifestations (forced thoughts or flight of ideas), affective features (panic terror), and psychosensory (ecmnesic hallucinations) or psychomotor (confusional automatism) symptoms accompanying some attacks; c) the loss of speech preceding the loss of consciousness and terminal generalized convulsions. 2. to establish the consequences of the lesion and of the temporal fits on the behaviour of the writer; a) associated hypoactivity (slowness of ideation and writing) and paroxysmal impulsiveness (violent unmotivated angry outbursts); b) disturbed verbal functions (difficulty in finding words); and c) diminished sexuality. As a conclusion, it must be admitted; a) that Flaubert suffered from an organic and not a psychogenic epilepsy, the existence of the latter currently being disputed; b) that this epilepsy modified the behaviour of the author without affecting his genius; c) that, as a result of this, the epilepsy of Flaubert, as that of Dostoïevski, should serve as a defense witness for the unfortunate epileptics thought to be destined for intellectual deterioration only because of the repetition of their seizures.