Animals and children in good health are generally cheerful and of optimistic temperament. As soon as they fall ill they become sad and melancholy until their recovery. We may infer from this that an optimistic view is correlated with normal health, whilst pessimism arises from some physical or mental disease. And so in the case of the prophets of pessimism, we may seek for the origin of their views in some affliction. The pessimism of Byron has been attributed to his club-foot, and that of Leopardi to tuberculosis, these two nineteenth century exponents of pessimism having died whilst young. Buddha and Schopenhauer, on the other hand, reached old age, whilst Hartmann died when sixty-four years old. Their diseases at the time when they formed their theories could not have been very dangerous, and none the less they took a most gloomy view of human existence. The recent historical investigations of Dr. Iwan Bloch[182] make it very probable that Schopenhauer, in his youth, contracted syphilis. There has been found a note-book of the great philosopher in which he wrote down the details of the severe mercurial treatment which he had to undergo. The disease, however, was not contracted until several years after the appearance of his great pessimistic work. Although we must attach due weight to the connection between disease and pessimism, we can assure ourselves that the problem is more complex than it appears at first sight. It is well known that blind people often enjoy a constant good humour, and, amongst the apostles of optimism, there has been the philosopher Duering,[183] who lost his sight during his youth. Moreover, it has been noticed that persons affected with chronic diseases frequently have a very optimistic conception of life, whilst young people in full strength may become sad, melancholic, and abandoned to the most extreme pessimism. Such a contrast has been well described by Émile Zola in his novel _La Joie de Vivre_, where a rheumatic old man, tried by severe attacks of gout, maintained his good humour, whilst his young son, although vigorous and in good health, professed extreme pessimism. I have a cousin who lost his sight in early youth. When he grew up he formed a most enviable judgment of life. He lived in his imagination and everything in life seemed to him good and beautiful; he married, and pictured his wife to himself as the most beautiful woman in the world, and thus he feared nothing more than the recovery of his sight. He had adapted himself to live without sight, and was convinced that the reality was much lower than his imagination. He feared that if he were able to see his wife she would appear to him less beautiful. I know a girl twenty-six years old, blind from her birth, the subject of infantile paralysis and liable to fits of epilepsy. She is nearly an idiot, lives in a carriage, and sees life from its best side. She is certainly the most happy member of all her family.