Despine, by his great work, _Psychologie Naturelle_ (1868), made a new and important step in criminology. Leaving aside the study of the criminal’s physical nature, he sought to make an exhaustive study of his mental nature. No one has done more than Despine to prove that what we should now call the instinctive criminal is, on the psychological side, a natural anomaly, a mental monstrosity. He brought into clear relief the unforeseeing imprudence, the entire lack of moral sensibility and of remorse, which characterise the instinctive criminal. He recognised that the criminal is not necessarily an insane or diseased person, and he showed that his abnormality is not of the kind that intellectual education can remedy. “No physiologist,” he said, “has yet occupied himself with the insanity of the sane;” he considered the criminal as “morally mad,” and therefore irresponsible. Maudsley, from an opposite philosophic standpoint, came to very similar conclusions. Without bringing any fresh contribution of importance, he re-affirmed emphatically the conclusions already reached. Speaking in his _Responsibility in Mental Disease_ (1872) of instinctive criminals, he remarks, “It is a matter of observation that this criminal class constitutes a degenerate or morbid variety of mankind, marked by peculiarly low physical and mental characteristics.” Like Despine, he drew from this the conclusion, since widely accepted, that the criminal, being morally insane and usually incurable, should be treated in the same way as the intellectually insane person. “If the matter be considered deeply, it may appear that it would, perhaps, in the end make little difference whether the offender were sentenced in anger and sent to the seclusion of prison, or were sentenced more in sorrow than in anger, and consigned to the same sort of seclusion under the name of an asylum. The change would probably not lead to an increase or to a decrease in the number of crimes committed in a year.” An artist as much as a man of science, master of a sombre and weighty style, illumined by vivid flashes of imagination, Maudsley by his numerous works popularised the new ideas, and is justly regarded abroad as a pioneer of criminal anthropology.