The good humour and megalomania of those affected with general paralysis of the insane also is well known. All such examples show that pessimism cannot be explained as depending on bad health. Examination of the state of mind of a pessimist may throw some light on the subject. There has been within my own circle a typical case of a person who went through a phase of life in which everything seemed as gloomy as possible. My intimate knowledge of him makes it possible to apply my observations to the matter under discussion. The subject was born of parents of good health and in comfortable circumstances, so that, from the beginning of his life, he was surrounded by a favourite environment. He lived in the country and escaped the diseases of childhood, so that he reached maturity in good health, and passed well through college and the university. Science attracted him, and he had the ambition to become a distinguished investigator. He threw himself into a scientific career with zeal and ability. His ardent disposition, although certainly favourable to work, was the cause of many troubles. He wished to succeed too quickly, and the obstacles he encountered embittered him. As he thought himself naturally talented, he conceived it to be the duty of his seniors to aid his development. And so, when he met with natural and very common indifference from those who had already become successful, the young man thought that there was a plot against him, to bring to nothing his scientific talents. From this view, many quarrels and difficulties arose, and as he could not overcome these sufficiently quickly, he fell into a mood of pessimism. In this life, he said to himself, the main thing is to adapt oneself to external conditions. According to Darwin’s law of natural selection, the individuals who do not succeed in adapting themselves go to the wall. The survivors are not the best but only the most cunning. In the history of the earth it has been seen that many lower animals have long survived creatures much higher in organisation and general evolution. Whilst so many of the higher mammals, the nearest relatives of man, have been crushed out of existence, simpler animals, such as evil-smelling cockroaches, have survived from the remotest times, and multiply in the neighbourhood of man in despite of his efforts to exterminate them. The animal series and human evolution itself show that delicacy of the nervous system, with its concomitant extreme development of the sensibilities, hinders the power of adaptation and brings with it insuperable evils. The least blow to his pride, or a slighting word from a comrade, threw this pessimist into a most painful condition. No, he would cry, it would be better to be without friends, if one is to be wounded so deeply by them. It would be best to seclude oneself in some remote spot and be engrossed in one’s work. He was very impressionable and a lover of music, and from his visits to the opera, he retained in his