In addition to cruelty, which we encounter not only in offenders against the person, but also see frequently in the form of a lack of sympathy, in usurers and cheats, the comparative psychology of criminals enables us to recognize in them as permanent qualities a recklessness and remorselessness,[26] and, in most cases, also an entire lack of integrity—that is to say, merely negative qualities—due to deficiency in the development of sensibility. Among positive qualities, a characteristic one is the fatuous vanity of many habitual criminals. It is a phenomenon of worldwide familiarity that that which in the life of a human being was at first a means merely, ultimately becomes an independent end—indeed, the sole aim. This we find also in the career of the criminal, to whom crime becomes a field for vain display. The art of pocket-picking, of housebreaking, of poisoning, ultimately becomes one pursued for its own sake. Some have thought this almost demoniacal; but there is nothing very singular in the practice of an acquired facility from the pure pleasure of its clever performance—art for art’s sake. Moreover, we see the same thing also in criminals who secretly destroy property or secretly commit arson. Here the art of remaining undiscovered is cultivated for its own sake. Lombroso gives a very elaborate description of several other psychical characters of criminals—of their religious life, and of their poetry and their literature, which latter, in bloodthirstiness and savage sensuality, closely resemble the tribal songs of the Australian blacks. In his subtle observation and description of the criminal psyche, in which he took note of the smallest details, and at the same time combined these details into a most effective general picture, making use alike of apparently trifling scrawls on prison walls and of comprehensive historical studies of crime, is certainly to be found his chief service. Here we find one of the finest examples known to modern psycho-pathology of the minute observation of details. Lombroso shows himself to be a true interpreter of nature, and a genius to whom, in the depth of his insight into human nature, we can, among the moderns, compare only Dostoieffsky, and, among those of an earlier day, only the brilliant criminal psychologist Shakespeare.