Gérard de Nerval in his book, _Le Rêve et la Vie_, after having confessed that he often wrote in a state of morbid exaltation, adds that the old saying _Mens sana in corpore sano_ is false, for many powerful minds have been allied to weak and diseased bodies. Conolly treated a man whose intelligence was aroused by the use of blisters, and another whose ability was called forth during the initial period of phthisis and gout. Cabanis, Tissot, and Pomme observe that certain febrile conditions provoke extraordinary mental activity. Sylvester remarks that during the nocturnal fever of what he describes as a fortunate attack of bronchitis he was enabled to reach the solution of a mathematical problem.[273] A man of genius, Maine de Biran, who was always ill, well expresses the influence of infirmities on genius, “The feeling of existence,” he writes, “is not found among the majority of men because with them it is continuous; when a man does not suffer he does not think of himself; disease alone and the habit of reflection enable us to distinguish ourselves.” It has frequently happened that injuries to the head and acute diseases, those frequent causes of insanity, have changed a very ordinary individual into a man of genius. Vico, when a child, fell from a high staircase and fractured his right parietal bone. Gratry, a mediocre singer, became a great master, after a beam had fractured his skull. Mabillon, almost an idiot from childhood, fell down a stone staircase at the age of twenty-six, and so badly injured his skull that it had to be trepanned; from that time he displayed the characteristics of genius. Gall, who narrates this fact, knew a Dane who had been half idiotic, and who became intelligent at the age of thirteen, after having rolled head foremost down a staircase.[274] Wallenstein was looked upon as a fool until one day he fell out of a window, and henceforward began to show remarkable ability. Some years ago, a cretin of Savoy, having being bitten by a mad dog, became very intelligent during the last days of his life. Cases have been recorded in which ordinary persons have displayed extraordinary intelligence after diseases of the spinal cord.[275] “It is possible that my disease [of the spinal cord] may have given a morbid character to my later compositions,” wrote with true divination the unfortunate Heine. And the remark does not apply to his later writings only. “My mental excitement,” he wrote, some months before his condition had become aggravated, “is the effect of disease rather than of genius. I have written verses to appease my suffering a little.... In this horrible night of senseless pain my poor head is flung backwards and forwards, shaking with pitiless gaiety the bells on my jester’s cap.”[276] Béclard turned from mere theories to experiment, after a stroke of apoplexy.[277] Pasteur’s greatest discoveries were made after a stroke of apoplexy. Bichat and Schroeder van der Kolk have observed