This address was delivered at the conference of the Philological Club at Naples, in 1899. The author points out that the neuroses are as old as man. He passes in review the different phases of these neuroses through which races have come as knowledge advanced. In the early ages as the result of a belief in a vindictive God, the neuroses assumed a melancholic form with religious ideas. The neuroses of the Greeks and Romans were coloured by the realism of the period. There followed an era in which all power was given to Satan, and in consequence an ascetic mysticism resulted, with the foundation of many religious orders, which spread all over Europe. Epidemics of hysterical and demoniacal possession were common. A new era dawned with greater liberty of thought and action. The author then gave statistics pointing to the great advances made in language and education, in our knowledge of the human body, and the laws governing it. From these have followed the neuroses of the present time—the weariness of life, the diffidence, the excitability, the unrest that needs always new and more powerful stimuli, the intolerance of restriction and of discipline that denotes a great hypertrophy of egoism which, in its most marked development, gives us the anarchist epidemic.