This work, whose aim it is to describe Lombroso, the man and the investigator, is not the place in which to describe his influence upon the Italian school of positive penology, or to describe the subsequent development of that school and its further influence upon the legislation and penal methods of the civilized nations. Science grows slowly; the study of the causes of crime demands time and patience, brings disillusionment, and leads to ever-fresh restatements of the old problems. The zeal of the reformer finds it difficult to tolerate the gradual transformation of the old machinery. He wishes at one stroke to rejuvenate old institutions, to sweep away the old rules. But science, which has to provide a basis for his efforts, is in its nature patient. The reformer’s zeal, which has to construct the new edifice, is not patient. Lombroso was to learn this from personal experience. It was not possible for him to remain at the standpoint of 1876. And, as reformer, he himself experienced many changes, especially as a result of his investigations into the categories of the criminal by passion, the habitual criminal, the occasional criminal, the criminaloid, the criminal lunatic, and the epileptic criminal. He and his school, in their efforts at reform, worked along two main lines: first, the reform of practical penal methods; and, secondly, the systematization of the general theory of punishment. The efforts of this school in relation to the system of punishment and the reform of penal methods are too well known for it to be needful to give here even the brief summary for which alone we should have space. But it is important to point out that the Italians, under Lombroso’s guidance, resolutely attacked the penal dogmas of the day, which it was necessary to overthrow before a reform of penal methods in the sense of social defence could possibly be effected. I shall merely make especial reference to the powerful influence for good exerted by the positive school in the direction of the amelioration and humanization of the horrible function of punishment, which represses so many crimes, but at the cost of so much suffering and of such numerous errors. Lombroso gradually came to believe that no useful purpose is effected by the provision of a great national apparatus intended to improve that which is unimprovable—_i.e._, the criminal nature; and that society could not be effectively safeguarded against its permanently dangerous members—_i.e._, the criminal natures—by means of protective measures of a transient duration.