The influence of this almost life-long malady upon his disposition cannot be estimated without taking into consideration the nervous strain which the impairment of so important a sense would induce in a person of Beethoven's temperament; to the mental effects of apprehension of future evil and the disappointments due to the futility of his efforts at obtaining relief must be added the purely physical consequences of the natural attempt at compensation which results in what may be denominated the fatigue of deafness. Normally we possess double the amount of hearing ordinarily required for the uses of life, and it is possible therefore to lose one half of the fullest amount of hearing without being appreciably affected by the loss. Ordinarily, therefore, our hearing-power is exercised without conscious exertion, but when this sense becomes impaired to a certain degree, an effort at hearing is necessary because of the loss of the sound of the more delicate qualitative overtones, such for instance as those which make the difference between the parts of speech most nearly resembling each other; to help out this deficiency the sight is called upon to watch the motion of the lips, and still later by a conscious effort those parts of a sentence which have been lost to hearing and have failed of detection by sight are mentally filled in from the context, three distinct brain processes being thus required to afford the information which came before unconsciously of effort. That such a nervous strain was part of the infliction which Beethoven suffered, is shown by his increasing disinclination for social intercourse and a tendency to lead as he says a life of isolation from all men. "You cannot believe," writes his friend Stephan von Breuning, "what an indescribable impression the loss of hearing has made upon Beethoven; imagine the effect on his excitable temperament of feeling that he is unhappy, then comes reserve, mistrust often of his best friends, and general irresolution. Intercourse with him is a real exertion, as one can never throw off restraint." Undoubtedly his deafness, with the consequent isolation from his fellows, had the effect of increasing the morbid peculiarities which were his inheritance, and of all his portraits extant there is none which so distinctly shows the face of the deaf man as that painted by his friend Maler, Vienna, 1812. "Beethoven's deafness," says Goethe, "has not hurt so much his musical as his social nature."