The greatest of all his services to sociology is that he threw light upon the reciprocal action between the organic and the social phenomena of human evolution in respect of a number of important details; but in doing this he avoided the onesidedness with which Marxism deduces the fate of the social organism from the economic basis of society, and avoided also the error of the dreamers who hope to explain the laws of social existence by regarding society as an organism similar to the mammalian organism, possessing distinct organs, each with its own peculiar functions. Lombroso was very powerfully influenced by Darwinism and by the evolutionary idea in general, more especially in the form elucidated by Herbert Spencer in his “First Principles.” As anthropologist, indeed, as regards the question of the origin of man and man’s place in nature, he was a forerunner of Darwin[35]; but in respect of the manner in which he presents the reciprocal action between the organic and the social, he is quite free from the analogies and homologies which led such men as Schaeffle and Spencer so widely astray. It was quite inevitable that Lombroso’s sociological thought should be powerfully stimulated by the view of his opponents that law is a product of the intellectual, not of the organic life of mankind, and that therefore it was not nature that produced criminals, but social and national processes. Thus it became necessary for him to prove—as in my opinion he succeeded in doing—that nature makes the criminal, but that society provides the conditions in which the criminal commits crimes. Nature creates the criminal—and here Lombroso occupies the same ground as Spinoza and Schopenhauer—inasmuch as it is through nature’s work that he comes to be born with predetermined tendencies of character—tendencies which are not altered after birth, but merely provided with opportunities for their manifestation. Lombroso identifies this predisposition of character with the so-called “moral insanity,” and there is no objection to this, provided we exclude the idea of an acquired illness. Above all, he regards this predisposition as an arrest at an earlier stage of development, as an atavism. Lombroso always presupposes the acceptance of the “fundamental biogenetic law,”[36] and for this reason is led to expect the occurrence of atavisms as the result of an arrest of development. Hence, what others speak of as degeneration is to him a pathological process leading to arrest of development. The course of his own mental development impelled Lombroso to take a further step, and to apply his customary methods to the study of the revolutionary, of the genius, of women, and of “mattoids.” If we now take a comprehensive view of all this, we find that Lombroso’s principal contribution to sociology involves the recognition of the following facts: